How to control cucumber beetles?

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Are your cucumber plants starting to lose its leaves? It’s likely you are having a problem with cucumber beetles.

I gardened for years without seeing these little pests in my garden. Then we moved and ever since we’ve had striped cucumber beetles after our plants.

Striped cucumber beetles are a small beetle only 1/4 inch long. They are yellow with black stripes and easy to see in your garden. At first, you might only notice one or two but left alone they will quickly multiply!

Contents

Contents

How To Get Rid Of Cucumber Beetles

Adult striped cucumber beetle overwinters in protected areas close to houses, fences and in the woods. In the spring when the weather starts to warm they begging to come out.

They will quickly find plants to eat and then lay their eggs around the base of the stem. The adult beetles eat the leaves, flowers, pollen and the larva eats the roots.

The cucumber beetle larva emerges later in the summer as an adult beetle for the second round of their lifecycle.

Cucumber beetles are aptly named because cucumbers are their favourite food. However, I’ve also found them eating zucchini and other summer squash, melons, and pumpkins in my garden.

Early in the season before these plants have sprouted I’ve also found them eating my tomatillos, ground cherries, peppers, and tomatoes! See these are nasty little pests.

Cucumber beetles can quickly devour young plants but their damage goes beyond only eating your crops. They also carry bacterial wilt disease.

Bacterial Wilt

Cucumber beetles carry the bacteria that causes bacterial wilt in their guts. As these beetles feed on your cucumber plants they can spread it through their mouths and feces.

Once the bacteria has been introduced it spreads quickly and causes the leaves of your cucumbers to wilt.

At first, you will notice your cucumber leaves start to flop down a little. Then other leaves around it will droop and then the stem. The bacteria spreads quickly and causes the entire plant to wilt and die.

There is little you can do to save an infected plant the best method is prevention.

Delayed Planting

You can try delaying your cucumber plantings by a few weeks. Some gardeners and market growers who have longer growing seasons have had luck by doing this.

When the cucumber beetles emerge in the spring if they don’t find food nearby they will fly to where they can find it. So by delaying your plantings any cucumber beetles that have overwintered in your garden should leave before your plants are up.

They will still be affected by the second round of beetles but by then your plants are larger and more established.

We live in a short zone 5 growing season so we have 3 months of summer and really we can get frosts into early June. Delaying planting isn’t always a good option for us.

A few years ago we were having a really bad year for cucumber beetles but I found an organic solution!

Diatomaceous earth works so well to keep cucumber beetles out of our garden!

Diatomaceous earth is a non-toxic powder that makes an excellent pest control for your garden. Diatomaceous earth is a fine powder that is made from ground up fossils of diatoms a type of algae with a hard shell.

When it’s ground up it would look something like broken glass shards under a microscope. You wouldn’t want to crawl through that and neither do the bugs!

To kill and prevent cucumber beetles I sprinkle diatomaceous earth all over my young plants and the ground around them. Most of the beetles are gone that day and a few days later I don’t find any at all.

Diatomaceous Earth Food Grade 10 LbFood Grade Diatomaceous Earth – 2 PoundBio-D Food Grade Diatomaceous Earth

I find Amazon has the best price and a wide selection of diatomaceous earth.

Now there are a few things you need to know.

Diatomaceous earth can kill any bug that crawls through it and that includes bees. So I try to not use this on my plants when they are flowering.

Instead, I use it when my plants first come up and as needed until they are well established. Now if my plants were flowering and under a heavy attack from cucumber beetles, yes I would still use the diatomaceous earth.

I would try to apply it mostly to the ground around the plants, though. This way it would get the beetles without affecting the pollinating insects.

Tips for using Diatomaceous earth

  • Apply diatomaceous earth sparingly and only use it on plants that are heavily affected by insects.
  • Apply diatomaceous earth when the bees are less likely to be out. This is early in the morning or late in the evening.
  • Apply diatomaceous earth on the soil around your plants where the pests are more likely to be and bees are not normally found.
  • Use a mask when applying diatomaceous earth, especially when it’s windy. It’s a gritty powder and it’s not a good idea to be breathing that in.

More Organic Cucumber Beetle Control Tips

Obviously using diatomaceous earth is my favourite way to kill cucumber beetles but there are other natural methods you can use to protect your cucumber plants too.

A big part of this is by attracting beneficial insects to your garden.

Beneficial Insects

You may be surprised to find out but ladybugs and lacewings will eat cucumber beetle eggs! So make sure you plant lots of flowers around your garden that attract these helpful insects to your garden.

You can get ladybugs to add to your garden here for a great price!

Another helpful insect in the garden is the spined soldier bug. It doesn’t look very friendly and is often mistaken for a squash bug, but this helpful insect is a real predator in your garden.

Spined soldier bugs have a very sharp proboscis that they use to literally suck the juices out of other insects. They are very helpful for getting rid of cucumber beetles but they also eat many other pests like cabbage worms and flea beetles.

Sticky Traps

Another method that works for killing striped cucumber beetles is to place yellow sticky traps near your cucumber plants. These sticky bug traps are the same color as the cucumber flowers and the adult beetles will be attracted to them.

Make sure to place the sticky traps out into your garden before the cucumbers start to flower for them to be the most effective.

Use Trap Crops

You can also plant trap crops out into your garden before your cucumber plants go in. Blue hubbard squash is a great trap crop for cucumber beetles because it produces a high amount of cucurbitacin starting when the plants are only 2 weeks old.

Plant these host plants on the edges of your garden and watch them closely for signs of cucumber beetles. Place yellow sticky traps around the plants to help catch the adult cucumber beetles when they first start showing up in your garden. Then dust the plants well with diatomaceous earth to kill the remainder.

Prevent Cucumber Beetles

Start taking measures early in the garden season to prevent damage from cucumber beetles. This starts by deciding what varieties of cucumbers you want to grow.

While there are none that are actually resistant to cucumber beetles planting cucumbers that are resistant to bacterial wilt will help a lot because the plants won’t be susceptible to the diseases the cucumber bugs carry.

Another way to deter these garden pests is to keep spraying a thin coating of kaolin clay over the leaves through the growing season. It creates a surface that insects really don’t like. I like this brand that comes in bulk for gardens and orchards.

One of the easiest ways to control cucumber beetles on your plants is to keep them covered with floating row covers. You’ll want to use a light weight one that is made for insect protection and not frost protection during the main growing season.

This cover will keep the adult beetles from landing on your plants. The only downside to this is that you would either have to pollinate the cucumber flowers by hand or remove the cover once the cucumbers start to flower so bees can pollinate the flowers.

I’ve tried many organic sprays over the years for different bugs in our garden. So far diatomaceous earth is the only natural method I’ve found that successfully control cucumber beetles.

Now that you’ve learned how to get rid of cucumber beetles organically I hope you’ll have a much more relaxing growing season!

Do you need an easy way to keep track of your garden? Click here to get your free printable garden journal.

Kim Mills is a homeschooling mom of 6 and lives on an urban homestead in Ontario, Canada. Blogging at Homestead Acres she enjoys sharing tips to help you save money, grow and preserve your own food.

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You know you might have a cucumber beetle problem if your plant leaves are yellowing, wilting, or have holes appearing on them, or if your seedling stems are being chomped on.

(Whether you’re starting your first garden or switching to organic, Rodale’s Basic Organic Gardening has all the answers and advice you need—get your copy today.)

The beetles swarm on seedlings, feeding on leaves and young shoots, often killing plants; they also attack stems and flowers of older plants and eat holes in fruit. Their feeding can transmit wilt and mosaic viruses to your plants. The beetles can be found across North America, mostly in the West.

Related: Everything You Need To Know About Growing Crisp Cucumbers

There are two types of pesky cucumber beetles: striped and spotted. Striped cucumber beetles mostly feed on circubit vegetables vegetables like cucumbers, squash, pumpkins, and beans, and rarely on other plants, while the similar spotted cucumber beetles feed on over 200 different crop and non-crop plants. They are both yellow, and and you can differentiate them by the shape of the black marks on their wing covers. Striped cucumber beetle adults are yellow, elongate, 1/4-inch beetles with black heads and three wide black stripes on wing covers (as opposed to the spots on the spotted beetle’s wing covers). Striped cucumber beetles lay eggs at the base of cucurbit plants and their larvae then feed on the roots of these plants. The adults feed on squash family plants, beans, corn, peas, and blossoms of many garden plants. Larvae feed on roots of squash family plants only, killing or stunting plants.

Related: 81 Border Plants That Are Better Than A Fence

A spotted cucumber beetle on a leaf. bkkm/getty

Life cycle of the cucumber beetle

Adults overwinter in dense grass or under leaves (so get rid of these right away to prevent a cucumber beetle infestation!), emerging in early spring to early summer. They eat weed pollen for 2 weeks, then move to crop plants, laying eggs in soil at base of plants. Eggs hatch in 10 days; larvae burrow into soil, feed on roots for 2 to 6 weeks, pupate in mid- to late summer. The larvae are slender, white grubs.

Adults typically emerge in 2 weeks to feed on blossoms and maturing fruit, with one to two generations per year. The spotted cucumber beetle is a bitdifferent, primarily laying its eggs on corn and other grasses such that the larvae of spotted cucumber beetles are not damaging to cucurbit crops.

Related: 14 Insects You Actually Want To Have In Your Garden

How to control cucumber beetles naturally

There are several strategies you can use if you spot cucumber beetles popping up in your garden. The first thing you can do to prevent them is to remove any dense grass, leaves, garden trash and other debris shortly after harvest to reduce their potential overwintering sites. The best course of action once you spot them should be to inspect plants frequently for these beetles and handpick or vaccum any that are discovered and remove them.

Another step can be to introduce a natural predator. Commercially available beneficial insects, such as ladybugs, green lacewing and the spined soldier bug, will feed on pest eggs. (Here are 10 beneficial insects you actually want to have in your garden.) Beneficial nematodes also work well to curtail immature stages developing in the soil.

Remove and destroy crop residues where adults overwinter; cover seedlings or plants with a floating row cover, and hand-pollinate covered squash family plants. You can also pile deep straw mulch around plants to discourage beetles from moving between plants. For uncovered plants, you can apply kaolin clay, especially to leaf undersides, and reapply after rain. The clay is a good natural mineral deterrent.

How to Get Rid of Cucumber Beetles

If you have ever grown cucumbers in your vegetable garden, then you have probably come across the cucumber beetle a time or two. If you have grown cucumbers before and never seen cucumber beetles on your plants, then you are lucky. Entire crops of cucumbers and squash can be lost due to this pest insect.

This little insect can be one heck of a nightmare for your cucumber plants. Here’s some information on identifying cucumber beetles, what kind of damage they can do to your cucumber plants, and some ways to prevent and eliminate them in your vegetable garden.

What Is a Cucumber Beetle?

Cucumber beetles are mostly bright yellow in color, have long antennae in the front, and are about 1/4-inch in length. They are winged making it easy to fly around fron plant to plant, and very difficult to capture.

You will find two different kinds of cucumber beetle – striped and spotted.

The spotted cucumber beetle is greenish yellow and has twelve black spots on its back. The striped cucumber beetle is yellowish orange and has three black stripes on its back.

It is very easy to confuse spotted cucumber beetles for ladybugs as they are very similar looking at first glance.

Ladybugs have short antennae while the cucumber beetle has very long string-like antennae.

Typical Damage Caused By Cucumber Beetles

Cucumber beetles feed on the soft leaves and stems of many vegetables in the curcubit family including cucumbers, squash, pumpkin, and melons.

The biggest threat cucumber beetles possess in the vegetable garden is they can spread mosaic viruses in cucumbers and other plants.

This disease will cause wilting and yellowing leaves, and ultimately death to the plant. Affected fruit can grow disfigured and bitter tasting.

Taking appropriate steps to prevent cucumber beetles can go a long way towards eliminating them from the vegetable garden. Monitoring your plants persistently throughout the season will help you to detect their presence early. This is important for keeping populations from getting out of control.

Most mature cucumber plants can handle a few cucumber beetles without much problems, but if cucumber beetles begin feeding on younger plants it could mean trouble.

Use Insect Barrier

You can use insect barrier cloth to cover cucumber plants to keep the insects from getting to them. Unfortunately, this will also block out pollinators so you may need to remove the barrier in the early morning hours to allow pollinators to access the blooms.

Attract Beneficial Insects

Plant flowers and other plants in, and around, your vegetable garden to attract beneficial insects, like ladybugs, lacewings, assassin bugs, and solider beetles into your garden. These beneficial insects pray on cucumber beetles and can reduce their numbers.

Use Specific Organic Pesticides

Specific organic pesticides can also be used in a controlled manner to reduce cucumber beetle populations. Neem oil and Insecticidal Soap can be used to help get rid of cucumber beetles.

These pesticides work by smoothering, so make sure to coat the insect pests with the neem oil or insecticidal soap well.

Use a Trap

Cucumber beetle traps can be placed around affected plants to lure and trap them as well.

The cucumber beetle is attracted to the trap, fly over to it and become trapped in and cannot get back out.

Place these traps within three to five feet of affected plants for best results.

Persistent Controls Get Rid of Cucumber Beetles

If you monitor your cucumber plants each day and stay on top of insect pest populations you can easily get rid of cucumber beetles and keep them out.

The biggest thing to remember is prevention is half the battle. There are also some cucumber variety that are resistant to mosiac virus and cucumber beetles, so check with your local garden center to see if they carry these.

Other Helpful Organic Pesticides & Fungicides

*Hover over the image for name

Cucumber Beetle, Management

Striped cucumber beetle is our most serious early-season pest in vine crops. These beetles spend the winter in plant debris in field edges, and with the onset of warm days and emergence of cucurbit crops, move rapidly into the field. Densities can be very high, especially in non-rotated fields or close to last year’s cucurbit crops. Adult feeding on cotyledons and young leaves can cause stand reduction and delayed plant growth. The striped cucumber beetle vectors (Erwinia tracheiphila), the causal agent of bacterial wilt, and this can be more damaging than direct feeding injury. Crop rotation, transplants, and floating row cover are cultural controls that help reduce the impact of cucumber beetles. Perimeter trap cropping gives excellent control with dramatic reduction in pesticide use.

For more detailed information on the identification, life cycle, crop injury, and cultural controls of this pest, please see our main Cucumber Beetle, Striped article.

Avoid early season infection with wilt. Cucurbit plants at the cotyledon and first 1-4 leaf stage are more susceptible to infection with bacterial wilt than older plants.

Thresholds and foliar controls

Beetle numbers should be kept low, especially before the 5-leaf stage. Scout frequently (at least twice per week for two weeks after crop emergence) and treat after beetles colonize the field. Early spot treatments of field edges can be helpful. The threshold depends on the crop. To prevent bacterial wilt in highly susceptible crops, we recommend that beetles should not be allowed to exceed one beetle for every 2 plants. Less wilt-susceptible crops (butternut, most pumpkins) will tolerate 1 or two beetles per plant without yield losses. Spray within 24 hours after the threshold is reached. Proper timing is key. There are a number of broad spectrum insecticides which can be used for foliar control (including Capture 2EC, Decis 1.5EC, Thoinex 50W, Asana, and Sevin). See the New England Vegetable Management Guide for more details.

Organic insecticides

OMRI-list insecticides available for use in organic cucurbits include kaolin clay (Surround WP), pyrethrin (Pyganic Crop Spray 5.0 EC), and spinosad (Entrust). In 2009 spray trials comparing these three products at the UMass Research Farm, kaolin was the most effective in reducing beetle numbers and feeding damage. There was a trend toward Surround WP being more effective when Pyganic or Entrust was mixed with it, but never significantly better than surround alone. Other studies have shown more efficacy from pyrethrin and spinosad. Surround should be applied before beetles arrive because it acts as a repellent and protectant — beetles do not “recognize” the plant and so do not feed — not a contact poison. With direct-seeded crops, apply as soon as seedlings emerge if beetles are active. Transplants can be sprayed before setting out in the field.

Systemic controls

Two systemic neo-nicotinoid products, imidacloprid (Admire Pro) and thiamethoxam (Platinum), are registered for use in cucurbits. In New England, Platinum is labeled for use specifically for striped cucumber beetle only in MA and CT. These are systemic insecticides that may be used as an in-furrow, banded, drench, or drip irrigation application to the seed/seedling root zone during or after planting/transplanting operations. DO NOT apply as a foliar spray.

Using systemics in direct seeded crops

It is important to get the insecticide into the soil to avoid photochemical breakdown; placing it in the furrow or irrigating it in can accomplish this. One of the most efficient systems for an in-furrow treatment is to attach an injector to the planter for placement at the seed level after the furrow is opened and before the seed drops. This has the advantage of one trip through the field and very precise targeting of material. Where it is applied to the soil surface, it should be watered in with irrigation (or rainfall) to move it to root depth for seedlings.

Using systemics on transplants

The best time to treat is about 1 day prior to planting in the field. We have observed effective results at rates of 0.01 ml Admire Pro per plant. See label for application rates. Caution should be used because phytoxicity can occur at high rates. Note: there are 29.6 milliliters (ml) in one fluid oz.

Another way to apply imidacloprid to transplants is through a water wheel planter. Use the same rate per plant as you would for a transplant drench and the rate of water per plant that fits your planter (e.g. 8 oz). Multiply by the number of plants and mix the total insecticide needed with the total water needed in the tank. Make sure your workers wear protective gear including chemical resistant gloves and allow time for uptake (1+ days) into leaves Note that the highest rate of uptake will be into new growth.

Systemic seed treatments

The Farmore DI-400 seed treatment from Syngenta combines a systemic insecticide with three different fungicides in a seed treatment. We haven’t tested it ourselves, but we’ve heard that results are good, with 20-25 days of SCB control and no reduction in germination or plant health. The price is relatively low, as the seed treatment adds about $2-$3 per 1,000 seeds. It’s registered for use on a wide variety of cucurbits, including cucumber, muskmelon, pumpkin, summer squash, winter squash, and watermelon.

Drip application

A drip system can be used for Admire or Platinum applications to either direct seeded or transplanted crops. Know your system well enough to know how long it will take to inject a given amount of concentrated solution (eg one bucketful) and to soak the area between emitters. Apply early enough to allow the plant roots and leaves to take up the material before beetles arrive. The system should be primed with water first, and the insecticide injected slowly for even distribution. Make sure to use enough water to soak the area between emitters. More emitters provide more even distribution of product.

Calculate the total needed based on the rate per 100 or 1000 ft of row and the number of row feet of line that will be treated. Place the total amount in the bucket with enough water for 20-30 minutes of injection. Charge the system with water first to get the soil wet. Turn on the Venturi or other injector, to inject slowly for even distribution (20 or 30 minutes). Then flush lines with clear water and to move product out and down.

Non-target effects

Bees are very susceptible to imidacloprid and thiamethoxam and could be affected by its presence in pollen if it is still at high levels in the plants at the time of flowering. Bees intoxicated by Admire or Platinum, like beetles, show unusual behaviors such as tremors, staggering, and falling over before dying. This could happen with bees at excessively high rates of these insecticides. The foliar formulation of imidacloprid (Provado)is not labeled for cucurbits, and the foliar formulation of thiamethoxam (Actara) has a label for cucurbits but may not be sprayed during bloom. Carbamates such as Sevin and synthetic pyrethroids should not be used during bloom to avoid killing bees. Given the high losses of hives over the past several years – which seems to be from multiple causes, only one of which is the pesticides used on crops that bees visit – taking precautions to protect both native and domestic bees is an especially important concern. Note that the 2010 edition of the New England Vegetable Management Guide gives rating for bee toxicity of insecticides in Table 20 (pg 49).

Resistance from overuse

The down side of systemic products might be that they are ‘too easy’. That’s not necessarily a bad thing for growers who are always too busy! However if these are overused on a routine basis, these products may well be lost to resistance in a fairly short time. Furthermore, they are not cheap. For a truly IPM approach, combine or alternate these materials with crop rotation, perimeter trap cropping, and field scouting followed by foliar sprays with other classes of insecticides to reduce the likelihood of resistance and keep use rates low. Perimeter trap cropping provides a large, untreated refuge which may delay resistance.

-Ruth Hazzard & Andrew Cavanagh, University of Massachusetts, updated for 2010.

Cucumber, Squash, Melon & Other Cucurbit Insect Pests

Cucumber Beetles

Cucumber beetle damage can occur on the watermelon fruit.
Barbara H. Smith, © 2018 HGIC, Clemson Extension

The spotted, striped and banded cucumber beetles are very harmful to cucurbits (members of the gourd family, including cucumbers, melons, pumpkins and squashes), particularly young plants. Beetles commence feeding on plants as soon as they emerge and either kill the plants or greatly slow growth. In cucurbit plantings throughout South Carolina, beetles have been observed entering the soil through cracks and feeding on seedlings below the soil surface. Beetles are present throughout the growing season and feed on all parts of the plant including the flowers and fruit.

Cucumber beetles also transmit bacterial wilt of cucurbits. This disease overwinters (survives the winter) in the intestines of the beetles and is scattered from plant to plant as the beetles feed. Infected plants eventually wilt and die. Many new varieties of cucurbits have resistance to bacterial wilt. Cucumber beetle larvae (immature forms) feed on the roots and bore into both roots and stems of cucumber plants.

The yellowish-green adult spotted cucumber beetle (Diabrotica undecimpunctata howardi) has 11 black spots and a black head with black antennae. The yellowish-white larvae have brown heads and are ¾-inch (19 mm) long when grown.

The yellow adult striped cucumber beetle (Acalymma vittatum) is about 1/5-inch (5 mm) long with three longitudinal black stripes on the top wings. The whitish larvae are about ⅓ inch (8.5 mm) when grown.

The adult banded cucumber beetle (Diabrotica balteata) is yellowish green with three bright green stripes or bands running across the wing covers. In a home vegetable garden, control measures include the use of fabric row covers, such as spun-bonded polyester. These covers provide an effective barrier between the insect and young plants. Remember to remove the covers during flowering to ensure pollination. Handpicking to remove the beetles is time-consuming but effective. In addition, several predators and parasites are enemies of cucumber beetles. Eliminate weeds in and around the garden.

Spotted cucumber beetle adult (Diabrotica undecimpunctata howardi).
J.P. Michaud, Kansas State University, www.insectimages.org

Striped cucumber beetle (Acalymma vittatum).
Clemson University – USDA Cooperative Extension Slide Series, www.insectimages.org

Banded cucumber beetle (Diabrotica balteata).
Ottens, University of Georgia, www.insectimages.org

Spider Mites

Two-spotted spider mites (Tetranychus urticae) can be a serious problem on cucurbits, especially watermelons and cantaloupes, during hot, dry weather. These tiny mites feed on the contents of individual cells of the leaves. This damage appears as pale yellow and reddish-brown spots ranging in size from small specks to large areas on the upper sides of leaves. Damage can develop very quickly and the mites can kill or seriously stunt the growth of plants. Because of their small size, spider mites are hard to detect until vines are damaged with hundreds of mites on each leaf. Certain insecticides applied at planting or as a foliar spray for insect control apparently contribute to severe outbreaks of mites on melons by killing their natural enemies.

Typical stippling damage to leaves from two-spotted spider mites (Tetranychus urticae).
Whitney Cranshaw, Colorado State University, www.insectimages.org

Extreme close-up of two-spotted spider mite (Tetranychus urticae).
David Cappaert, Michigan State University, www.insectimages.org

Insecticidal soaps generally offer adequate control when applied before the numbers are too high. Make two applications five days apart. Squash leaves are easily burned by insecticidal soaps, so use the most dilute concentration recommended, and use sparingly. Do not spray plants in direct sun or if plants are drought stressed. Spider mites can also be controlled with neem oil extract. Mites can be removed with a strong spray of water. Predatory mites and beneficial insects such as lady beetles and minute pirate bugs are important natural controls.

Melon Aphids

Melon aphids, also known as cotton aphids (Aphis gossyppi).
Mississippi State University Archive, Mississippi State University, www.insectimages.org

Melon aphids (Aphis gossyppi) and several other aphid species attack cucurbits, particularly melons and cucumbers. Melon aphids vary in size and color from light yellow to green to black. Some are winged, while others are wingless.

They are found chiefly on the underside of the leaves, where they suck the sap from the plants and cause a reduction in the quality and quantity of the fruit. Infested leaves curl downward and may turn brown and die. The melon aphid also is one of the chief agents in transmitting Cucumber mosaic virus. Usually, cucurbits are not attacked by aphids until the vines form runners.

Consider natural controls when making treatment decisions. Beneficial insects are extremely important in keeping aphid populations in check. Infestations usually are higher in hot, dry summers following cool, dry springs, which have reduced the efficiency of the natural enemies. In addition to natural enemies, you can spray leaves with soapy water, then rinse with clear water. Spraying with insecticidal soap, planting in aluminum foil-covered beds and filling yellow pans with water to trap the aphids are also effective control measures.

Squash Bugs

The squash bug (Anasa tristis) is one of the most common and troublesome pests in the home vegetable garden. Squash plants frequently are killed by this sap-feeding pest. Leaves of plants attacked by the bugs may wilt rapidly and become brittle. Winter varieties of squash, such as Hubbard and Marrows, are much more severely damaged by the squash bug than other varieties. Control is required to protect squash in the home garden.

The adult squash bug is rather large, brownish black, and flat-backed. It is about ⅝-inch (1.6 cm) long and approximately ⅓ as wide. The young, called nymphs, are whitish to greenish gray, with black legs. They vary in size from tiny, spider-like individuals when first hatched, to maturing nymphs, which are nearly as large as the winged adults.

Squash bugs overwinter in protected places as unmated adults. They appear rather slowly in the spring. They mate and begin laying egg clusters about the time vines begin to grow and spread. Eggs are yellowish brown to brick red in color and are laid in clusters of a dozen or more on the leaves. They hatch in about 10 days into nymphs that become adults in four to six weeks. Only one generation of bugs develops each year. New adults do not mate until the following spring.

The squash bug is secretive in its habits. Adults and nymphs may be found clustered about the crown of the plant, beneath damaged leaves, and under clods or any other protective ground cover. They scamper for cover when disturbed. The secretive nature of squash bugs can be used to your advantage in controlling these pests. Place a small, square piece of old shingle or heavy cardboard under each squash plant. As bugs congregate under it for protection, simply lift the trap and smash them with your hoe (or shoe). Other control methods include early planting and removing eggs and nymphs by hand.

Remove and destroy vines and discarded fruit after harvest to eliminate overwintering sites. Early detection of squash bugs is very important, as they are difficult to control and can cause considerable damage. Apply insecticides when nymphs are small, as adults are difficult to kill.

Older squash bug nymphs (Anasa tristis).
Whitney Cranshaw, Colorado State University, www.insectimages.org

Squash bug egg clusters (Anasa tristis).
Whitney Cranshaw, Colorado State University, www.insectimages.org

Squash Vine Borers

The squash vine borer (Melittia cucurbitae) ranges from Canada to Argentina and is the most serious enemy of squashes and gourds. It causes much trouble where only a few plants are grown in gardens. It rarely attacks cucumbers and melons. Great variations exist in the susceptibility of squash and pumpkin varieties. Butternut and Green-Striped Cushaw varieties are practically immune to attack, but Hubbard squash is highly susceptible.

Damage is caused by larvae (immature forms) tunneling into stems. This tunneling often kills plants, especially when the larvae feed in the basal portions of vines. Sometimes fruits are also attacked. Sudden wilting of a vine and sawdust-like insect waste coming from holes in the stem are evidence of attack.

The adult is one of the moths known as “clear wings” because the hind wings are almost without scales. It is 1½ inches (3.8 cm) in wing expanse and metallic greenish black in color. Hind legs are fringed with black and orange hairs, and markings of similar color occur over much of the abdomen.

The moths are day fliers and are often mistaken for wasps. Larvae are white, heavy-bodied and considerably over 1 inch (2.54 cm) long when fully grown.

The insect overwinters in the soil as a larva or pupa (a non-feeding stage where the larva changes to an adult) enclosed in a cocoon. Moths emerge in early summer and lay eggs on the stems of the plants, usually late May in the South. Upon hatching, larvae bore into vines and complete their development in four or more weeks. Then they leave the plant, crawl into the soil, spin a cocoon and transform to a pupa. There are two generations in South Carolina.

In a vegetable garden, various measures can be taken to control this pest. Till the soil in late winter to expose overwintering insects. Rotate squash to another location in the garden each season. Destroy vines that have been killed to break the life cycle. You can slit the infested vine lengthwise and remove borers or kill them with a long pin or needle. Place soil over slit stem after removing the borer to encourage root development, and keep plants well watered. Plant as early as the weather allows since borers do not emerge until early summer.

Tromboncino is an Italian heirloom cultivar of the species Cucurbita moschata, aka the butternut squash. Most butternuts are grown as winter squash where the fruit are harvested when mature, sweet, and dense. Tromboncino squash, however, are harvested and eaten when the fruits are young and tender, like summer squash. The best part is that all butternut squashes are essentially immune to squash vine borer due to the species’ dense, solid stems. This trait holds for Tromboncino as well. For more information, please see: https://hgic.clemson.edu/tromboncino-squash/

Squash vine borer larva (Melittia cucurbitae) and damage.
Alton N. Sparks, Jr., University of Georgia, www.insectimages.org

Close-up of squash vine borer larva (Melittia cucurbitae).
Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org

Pickleworms

The pickleworm (Diaphania nitidalis) severely damages cucumbers, cantaloupes, summer squash and pumpkins. It also feeds on other cucurbits, such as winter squash, and watermelons, but usually does little damage.

Pickleworm damage occurs when the caterpillars tunnel in flowers, buds, stems and fruits. They prefer the fruits. Frass (sawdust-like insect waste) often protrudes from small holes in damaged fruits. At times, damaged fruits cannot be recognized until they are cut open. Damaged fruits are not edible. Flowers, buds, and sometimes entire plants may be killed.

In South Carolina, pickleworms starve or freeze to death during the winter. They overwinter in Florida and spread northward each spring. Severe damage usually does not occur before summer in South Carolina. Heavy populations generally do not build up before the first flower buds open; however, late crops may be destroyed before blossoming. The pickleworm has complete metamorphosis, passing through four distinct stages (egg, larva, pupa and adult) during development.

Eggs are yellow, irregularly shaped and resemble grains of sand. They are laid singularly or in small groups on leaves and hatch in three to four days.

Larvae feed first on buds, blossoms and tender terminals, but soon move to the fruits. These brown-headed caterpillars molt (shed their skin) four times before they become about ¾-inch (1.9 cm) long and fully -grown in nine to 28 days. The body is yellowish white at first, but many reddish-brown spots appear on the back after the first molt. After the last molt, the caterpillar loses its spots and becomes solid green or copper. Finally, the caterpillar stops feeding, becomes pink to pale green and spins a thin silk cocoon around itself, usually within a folded-over portion of a leaf where it pupates (becomes a pupa).

Pupae (non-feeding stage where the larva changes to an adult) are light to dark brown and slightly more than ¾-inch long. Pupae are usually found in a rolled leaf. However, they have been found inside cantaloupe and summer squash in rare instances. Adults usually emerge after seven to 10 days.

Adults are brownish-yellow moths that have a rounded brush of hairs at the rear of the body. The brownish-yellow wings have a purplish sheen, translucent yellow-white centers and a spread of about 1 inch (2.54 cm). Moths are active at night.

Select early maturing varieties and plant as early as possible before pickleworm population peaks. Destroy damaged fruit and crush rolled sections of leaves to kill pupae. The more resistant varieties are: Butternut 23, Summer Crookneck, Early Prolific Straightneck, and Early Yellow Summer Crookneck.

Begin spraying susceptible cucurbits for pickleworms when the first buds or flowers appear and spray every 4 to 7 days with Bacillus thuringiensis (Bt) or every 7 days with spinosad. Always spray in the evening to enhance control and to reduce the impact to pollinating insects. See Table 2 for products containing Bt or spinosad.

Pickleworms bore into cucurbit fruit, and their frass is pushed out.
Joey Williamson, ©2016 HGIC, Clemson Extension

Pickleworm larvae (Diaphania nitidalis) inside fruit.
Clemson University – USDA Cooperative Extension Slide Series, www.insectimages.org

Squash Beetles

The squash beetle (Epilachna borealis) is one of two species of Coccinellidae known to occur in the United States that eat plant material rather than other insects. The squash beetle feeds upon the leaves of cucurbits. The other species, the Mexican bean beetle (Epilachna varivestis), a close relative of the squash beetle, is a serious bean pest.

The adult of the squash beetle overwinters in crop debris. All other lady beetles are beneficial because they feed on insect pests such as aphids and scale insects.

Adult squash beetle (Epilachna borealis), with spiny larva at left. Clemson University – USDA Cooperative Extension Slide Series, www.insectimages.org
Destroy crop residues after harvest and reduce overwintering sites by tilling.

Control of Cucurbit Insects

Table 1 lists the natural and conventional contact insecticides for the control of insect pests of cucumbers, squash and melons. However, limit the use of broad-spectrum contact insecticides, such as malathion, bifenthrin, cyhalothrin, cyfluthrin, permethrin, and pyrethrin, all of which kill beneficial predators and parasites of insect pests. Monitor the vegetables for the buildup of insect pests. Natural, less toxic pesticides may give good control and should be tried first.

Table 2 lists examples of available brands and products of natural and contact insecticides labeled

for use on cucumbers, squash and melons. It also gives the pre-harvest interval (PHI) for each insecticide, which is the number of days to wait between insecticide application and harvest.

For aphids or spider mites use insecticidal soap sprays first. Control heavy populations of aphids or spider mites with sprays of neem oil extract. Cucumber beetles or squash beetles can be controlled effectively using carbaryl (Sevin), but wait three days after spraying before harvest.

For vine borers and pickleworms control after mid-June, apply neem oil extract weekly, and spray in the evening to not kill pollinating insects. Bifenthrin, cyhalothrin, or cyfluthrin will control cucumber beetles, squash bugs, squash vine borers and pickleworms, but wait 3, 3, or 7 days, respectively, after spraying before harvest.

Table 1. Natural, Less Toxic Pesticides & Contact Pesticides to Control Cucurbit Insect Pests.

Pests Natural, Less Toxic Pesticides Contact Pesticides
Melon Aphids Insecticidal soap
Neem oil extract
Pyrethrin
Bifenthrin
Malathion
Cyhalothrin
Cyfluthrin
Cypermethrin
Cucumber Beetle Pyrethrin
Neem oil extract
Bifenthrin
Cyhalothrin
Cyfluthrin
Cypermethrin
Squash Beetle Pyrethrin
Neem oil extract
Bifenthrin
Cyhalothrin
Cyfluthrin
Malathion
Cypermethrin
Pickleworms Bacillus thuringiensis (B.t.)
Pyrethrin
Neem oil extract
Spinosad
Bifenthrin
Cyhalothrin
Cyfluthrin
Cypermethrin
Squash Vine Borer Neem oil extract Bifenthrin
Cyhalothrin
Cyfluthrin
Cypermethrin
Squash Bugs Neem oil extract Bifenthrin
Cyhalothrin
Cyfluthrin
Malathion
Cypermethrin
Spider Mites Insecticidal soap
Neem oil extract
Malathion
Bifenthrin

Table 2. Examples of Insecticides for Cucumber, Squash & Melon Pest Control.

Pesticide Active Ingredient Pre-Harvest Interval (PHI) in Days Examples of Brand Names & Products
Natural, Less Toxic Insecticides
Bacillus thuringiensis
(B.t.)
0 Monterey B.t. Concentrate
Natural Guard Caterpillar Killer Spray with Bt Concentrate
Garden Safe B.t. Worm & Caterpillar Killer Concentrate
Southern Ag Thuricide Spray Concentrate
Tiger Brand Worm Killer Concentrate
Insecticidal Soap 0 Bonide Insecticidal Soap Multi-Purpose Insect Control Conc.; & RTU1
Espoma Earth-tone Insecticidal Soap Concentrate; & RTU1
Natural Guard Insecticidal Soap Concentrate; & RTU1
Safer Brand Insect Killing Soap Concentrate; & RTU1
Garden Safe Insecticidal Soap Insect Killer Concentrate; & RTU1
Whitney Farms Insecticidal Soap RTU
Neem Oil Extract 0 Bonide Neem Oil Fungicide, Miticide & Insecticide Concentrate; & RTU1
Concern Garden Defense Multi-Purpose Spray Concentrate
Ferti-lome Rose, Flower & Vegetable Spray Concentrate
Garden Safe Fungicide 3 Concentrate; & RTU1
Monterey 70% Neem Oil Fungicide, Insecticide & Miticide Conc.; & RTS2
Southern Ag Triple Action Neem Oil Concentrate
Safer BioNeem Insecticide & Repellent Concentrate
Pyrethrin 0 Bonide Pyrethrin Garden Insect Spray Concentrate
Southern Ag Natural Pyrethrin Concentrate
Monterey Take Down Garden Spray Concentrate; & RTU (w/ canola oil)
Monterey Bug Buster-O Concentrate
Espoma Earth-Tone Insect Control Concentrate (w/canola oil)
Spinosad 3 Bonide Captain Jack’s Dead Bug Brew Concentrate; & RTS2; & RTU1
Bonide Colorado Potato Beetle Beater Concentrate
Ferti-lome Borer, Bagworm & Leafminer Spray Concentrate
Monterey Garden Insect Spray Concentrate
Natural Guard Spinosad Landscape & Garden Insecticide RTS2
Ortho Insect Killer Tree & Shrub Concentrate
Southern Ag Conserve Naturalyte Insect Control Concentrate
Contact Insecticides
Bifenthrin 3 Ferti-lome Broad Spectrum Insecticide Concentrate
Ortho Bug-B-Gone Insect Killer for Lawns & Garden Concentrate; & RTS2
Cyfluthrin 3 Bayer Bio Advanced Vegetable & Garden Insect Spray Concentrate; RTS2; RTU1
Cyhalothrin (lambda) 7 Martin’s Cyonara Lawn & Garden Concentrate; & RTS2
Spectracide Triazicide Insect Killer for Lawns & Landscape Conc.; & RTS2
Cypermethrin 1 GardenTech Sevin Insect Killer Concentrate; & RTS2
Malathion 1 Bonide Malathion Concentrate
Gordon’s Malathion 50% Spray Concentrate
Hi-Yield 55% Malathion Insect Spray Concentrate
Martin’s Malathion 57% Concentrate
Ortho Max Malathion Insect Spray Concentrate
Spectracide Malathion 50% Insect Spray Concentrate
Southern Ag Malathion 50% EC
Tiger Brand Malathion 50% Spray Concentrate
PHI = Pre-harvest interval or number of days to wait after spraying before harvest.
1 RTU = Ready to Use (pre-mixed spray bottle)
2 RTS = Ready to Spray (hose-end applicator)

Striped cucumber beetle (top) and spotted cucumber beetle (bottom).

Karen Delahaut, UW-Madison Fresh Market Vegetable Program
Revised: 8/19/2010
Item number: XHT1025

There are two common species of cucumber beetles in Wisconsin: the striped and spotted. The striped cucumber beetle is the more serious problem in the state. Cucumber beetles are a problem on vine crops because they transmit the bacterial wilt organism, Erwinia tracheiphila. Vine crops attacked by cucumber beetles include cucumbers, muskmelons, watermelons, squash and pumpkins. However, only cucumbers and melons are susceptible to bacterial wilt.

Appearance:
The striped cucumber beetle (Acalymma vittatum) is 1∕5 inch long and yellow-green in color with three black stripes running the length of its body. It is often confused with western corn rootworm beetles that are not a pest of vine crops, but are often found feeding on the pollen of cucurbit blossoms. To distinguish between the two, look at the underside of their abdomens. Striped cucumber beetles have black abdomens while the abdomens of western corn rootworms are yellow-green. Spotted cucumber beetles (Diabrotica undecimpunctata) are yellow-green with 12 black spots on their backs.

Symptoms and Effects:
Cucumber beetle larvae feed on roots and stems, and can stunt or kill seedlings or transplants. Adults feed on stems, foliage and fruit. More importantly, these beetles transmit the bacterium (Erwinia tracheiphila) that causes bacterial wilt. Adults pick up the bacterium when they feed on infected weeds in early spring. When the beetles begin feeding on cucumbers and muskmelons (bacterial wilt is not usually a problem in pumpkins and squash) they spread the bacterium either through their feces or contaminated mouthparts. Once the bacterium is in the plant, it travels through the vascular system and causes blockages of the vessels. The first symptom of bacterial wilt is a distinct wilting of individual lateral leaves. Eventually, the entire plant wilts and dies. To diagnose this disease, cut through a wilted stem and hold the cut ends together for 10 seconds. Slowly pull the ends apart and look for white, viscous material (that looks like a spider’s silk) that stretches between the two stem pieces. This material is a combination of plant sap and the bacterial wilt bacterium. Adult cucumber beetles are such effective carriers of the bacterium that serious crop damage can occur if only 10% of the beetles are carriers.

Life Cycle:
Striped cucumber beetles overwinter as adults in protected areas. They become active in mid to late May. Females lay their eggs in the soil at the base of curcurbits (i.e, cucumbers, muskmelons, etc.). The beetles are attracted to the chemical cucurbitacin that is produced by the plants. The small white larvae feed on plant roots for two to three weeks before pupating in the soil. Striped cucumber beetles have one generation per year. The spotted cucumber beetle does not overwinter in Wisconsin. Adults migrate north in early to mid-July. As a result of this late appearance, they are seldom a serious problem.

Scouting Suggestions:
Plants infected with the bacterial wilt pathogen will not recover. Therefore, controlling cucumber beetles early in the season is very important in order to prevent the initial spread of the pathogen. Scout fields for adult beetles two to three times per week early in the season, and weekly thereafter. Pay particular attention to field edges where beetles tend to congregate initially. Treat when there are more than four to five adults per 50 plants. When beetle populations are high (i.e., in excess of 20 per plant) transmission of the bacterial wilt organism is likely to occur before insecticides have a chance to control the beetles.

Control
Non-Chemical:
Non-chemical control can be achieved in small plantings by covering the plants with floating row covers to keep the beetles out. Make sure you uncover flowering plants to allow bees to enter and pollinate the plants. If bacterial wilt infections have already occurred, remove the diseased plants immediately to prevent the spread of the pathogen while insects are present.

Chemical:
There are several insecticides available for control of cucumber beetles. Refer to UWEX publication A3422 “Commercial Vegetable Production in Wisconsin” for a complete listing of available products. If the insecticide carbaryl is selected, care must be taken when making applications while bees are present. Applications should be made late in the day to reduce bee mortality. Adios® is a relatively new insecticide that combines cucurbitacin, the chemical that attracts cucumber beetles to vine crops, with a very small amount of carbaryl. The cucurbitacin causes the beetles to feed compulsively and ingest the insecticide, while reducing bee mortality.

For more information on cucumber beetles:
See UW-Extension Bulletin A3422, or contact your county Extension agent.

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Tags: insect, pest Categories: Vegetable Problems

Stop Cucumber Beetles in Your Garden

Cucumber beetles are nasty little pests that attack cucumbers and related plants (squash, melons, pumpkins) throughout the growing season. The beetles look like 1/4-inch-long insects that are yellow-green in color with a series of black stripes or spots. Watch for them from spring to fall.

They typically eat holes in the leaves and hide out on the bottom side of the foliage. Their green color makes them difficult to detect.

You may first notice them in spring; the beetles eat the leaves of your seedlings. The adults lay eggs near the plants; the eggs hatch into a colony of tiny grubs that eat the plant roots. The adults will also eat leaves and flowers on adult plants.

If that’s not bad enough, the pests also carry and spread a disease called bacterial wilt. Plants infected with the disease begin to wilt and die. If you cut a leaf from the plant and look closely, you may see a stringy white substance (that looks like mucus) where you cut off the leaf.

Controlling Cucumber Beetles

Row covers: Protect plants with floating row covers in early spring. These row covers create a barrier that keeps the insects out but allows air, light, and moisture to reach the plants. Be sure to remove the row covers when your vegetable plants grow too large or when the temperatures heat up in summer.

Hand picking: If there aren’t a lot of cucumber beetles, picking them off by hand and dropping them in a bucket of soapy water is a safe, budget-friendly means of control.

Clean up in fall: Keep your vegetable garden clean. The pests often overwinter in garden debris — so composting all dead foliage at the end of the season and tilling the garden each fall will help keep the pest under control.

Attract beneficial insects: Planting flowers, such as marigolds, calendula, sunflower, daisy, alyssum, or dill nearby can attract beneficial insects that attack and eat cucumber beetles.

Insecticidal soaps: Insecticidal soaps will kill the beetles, but must be applied on a regular basis in heavy infestations.

Insecticides: A number of insecticides also effectively kill cucumber beetles. Be sure to follow the package directions carefully.

© 2006 Plant Management Network.
Accepted for publication 3 August 2006. Published 20 October 2006.

Use of Neonicotinoid Insecticides to Manage Cucumber Beetles on Seedling Zucchini

Paul McLeod, Professor, Department of Entomology, Agri 321, University of Arkansas, Fayetteville 72701

Corresponding author: Paul McLeod. [email protected]

McLeod, P. 2006. Use of neonicotinoid insecticides to manage cucumber beetles on seedling zucchini. Online. Plant Health Progress doi:10.1094/PHP-2006-1020-01-RS.

Abstract

The use of neonicotinoid insecticides applied into soil at planting and when zucchini plants had two true leaves was effective against both the spotted (Diabrotica undecimpunctata howardi Berber) and the striped cucumber beetles. At 17 days after planting, significant increases in mean numbers of dead cucumber beetles were detected in all plots receiving insecticides at planting when compared to non-treated plots. All insecticides applied at planting resulted in significant reductions in feeding damage ratings. The duration of residual toxicity was long with the insecticide applied at planting. Dead beetles were detected in treated plots on each sample date throughout the 56-day test. When seeds were dipped in either a 0.043 or 0.086% a.i. imidacloprid mixture, emerging zucchini seedlings were effectively protected from cucumber beetle feeding.

Introduction

Commercial production of zucchini squash, Cucurbita pepo var melopepo (L.) Alef., and several other cucurbits has increased in the south-central US in recent years. Reasons for this increase include a desire to diversify crops from historically common agronomic crops like cotton and soybean, high profit potential, and increased demand by the food processing industry and fresh market consumers (William Russell, Allen Canning Co., Siloam Springs, AR, personal communication). With these high-value crops, any threat to production is often regarded as serious and management is generally extensive. Among the threats to cucurbit production, insects are often considered a major pest. Generally, the most common and destructive insect pests of cucurbits in the south-central US is the cucumber beetle complex. Soon after seeds germinate and seedlings emerge, the new plants are attacked by cucumber beetles including both the spotted (Diabrotica undecimpunctata howardi Berber) and the striped cucumber beetles. Adult beetles pass the winter and early spring months in weeds and brush near production fields (1,6). Although beetles can be found feeding on several non-cucurbit hosts, they prefer cucurbits and are capable of inflicting severe damage to emerging seedlings. When numbers are high, as often occurs in the Arkansas River Valley and southwestern Missouri, their feeding may result in death of cucurbit seedlings. Current management is centered on early detection of adults and damage and use of insecticides applied to foliage. Although several insecticides are effective against cucumber beetles, migration of additional beetles from surrounding areas together with rapid growth of new plant tissue with no effective insecticide residue, may require multiple applications. Depending on location and cucumber beetle population level, the number of foliar sprays can vary from 1 to more than 5 (2,7). Once plants develop several true leaves, the beetle impact greatly decreases and further management of cucumber beetles is generally not justified.

Most of the newer insecticides possess improved safety characteristics to applicators and to the environment yet retain high toxicity to pest insects. Among these is a group of insecticides called neonicotinoids, which are synthesized with the active component of nicotine embedded within the insecticide molecule. Properties possessed by neonicotinoids include low mammalian toxicity, reduced effects on non-target insects and low potential for environmental hazards (8). Neonicotinoid insecticides may be applied to soil (drench), seeds, and foliage (3,4,5). Another characteristic of neonicotinoids is their systemic activity, i.e., rapid uptake, especially through the roots, and translocation throughout the plant (9).

Neonicotinoids have been available in agronomic crops for almost 10 years. Labeling constraints and limited potential for profit, however, have delayed their development in horticultural crops. Recently the neonicotinoid imidacloprid has been registered for use on many vegetables. Although it was originally targeted against piercing and sucking insects such as aphids, it has been shown to have activity against a wide range of insect pests including Coleoptera (1). The objective of this study was to evaluate at-planting soil or seed applications of neonicotinoid insecticides as an alternative to multiple foliar insecticide applications for cucumber beetle management in zucchini.

Soil Application Trial 2002

Field tests were initiated during the 2002 production season to explore the potential for replacing multiple foliar insecticide applications with the soil applied neonicotinoid insecticides imidacloprid (Admire 2SC, Bayer CropScience, Research Triangle Park, NC) and thiamethoxam (Platinum 2SC, Syngenta Crop Protection Inc., Greensboro, NC). Plots were located on the University of Arkansas Vegetable Station, Kibler, AR, and consisted of a single six-foot-wide bed 35 ft long. Experimental design was a randomized complete block with four replications. ‘Black Beauty’ zucchini squash was planted with a single-cone Hege planter on 29 April 2002. A single seed was placed every 1 ft within each plot. Insecticide treatments at planting were applied within the planting furrow with a single TeeJet 8002E nozzle positioned just behind the seed tube and in front of the press wheel. The sprayer was propelled with CO2 and calibrated to deliver 2864 ml/1000 row ft at 25 psi (126 ml/15 sec). Planter speed was 2 mph or 341 sec/1000 row ft. Additional imidacloprid and thiamethoxam insecticide treatments were applied on 16 May when adult cucumber beetles reached the threshold of 2 per seedling (two unfolded true leaves). Insecticides were applied as described for the at-planting applications with the exception of treatment location within the bed which follows. A 1.5-inch-wide plow with open bottom was fitted with the single nozzle of the sprayer and driven at 2 mph with a Kubota tractor approximately 3 inches from one side of the drill line. Depth was approximately 4 inches. Sampling was initiated on 16 May (17 days after planting) when plants had two true leaves. Five sample areas, each 18 inches × 18 inches, were randomly selected along the drill line of each plot. Plants and ground within each of the five areas were searched for dead (inability to walk) striped and spotted cucumber beetles. Also, within each sample area the two cotyledons of each of two plants were rated for cucumber beetle feeding. Ratings were 0 (no damage), 1 (1 to 20% foliar loss), 2 (21 to 40% foliar loss), 3 (41 to 60% foliar loss), 4 (61 to 80% foliar loss), or 5 (>80% foliar loss). All plots also were sampled on 22 May (23 days after planting). To estimate the duration of residual toxicity within the plants, counts of dead beetles were taken 39 and 53 days after planting. Measured variables included damage ratings and numbers of dead beetles. Data were analyzed with ANOVA and when F values were significant means were separated with LSD (SAS Institute Inc., Cary, NC).

Soil Application Trial 2003

Plots were again located on the University of Arkansas Vegetable Station, Kibler, AR. ‘Black Beauty’ zucchini seeds were planted on 30 April as described above. Plot and experimental design and insecticide application were similar to those for 2002. Imidacloprid and thiamethoxam were again tested along with dinotefuran (Dinotefuran 20% SC, Valent Corp., Walnut Creek, CA).

Seed Treatment Trial 2004

In order to further reduce the amount of applied insecticide a study was initiated 2004 to explore the use of imidacloprid treated seeds for cucumber beetle management. Imidacloprid was diluted in water to produce the following concentrations: 0, 0.002, 0.009, 0.017, 0.043, and 0.086% a.i. Approximately 120 ‘Black Beauty’ zucchini seeds were placed into 150 mm diameter Petri dishes containing one of the concentrations. Seeds were removed after 10 min and placed on paper toweling. The following day, 28 June, dry seeds were transferred to the field for planting. The plot was located along the edge of a commercial zucchini field 12 miles east of Neosho, MO. Soil type was sandy loam. Seeds were hand planted and spaced two feet apart in a single row that ran the length of the field. Established zucchini plants were located east of the plot and field corn was located west of the field. Both areas provided large populations of cucumber beetles. Experimental design was a randomized complete block with 4 replications. Sampling included dead beetle counts and damage ratings as described above. Data were analyzed with ANOVA and LSD.

Because of the lack of information on use of imidacloprid as a cucurbit seed treatment, a test was initiated to determine the phytotoxic effects. Seven commonly-grown cucurbit cultivars were selected for testing. Seeds were obtained from Green Seed Co. Inc., Springfield, MO and included ‘Black Diamond’ watermelon and Nakai; ‘Straight 8′ cucumber (Cucumis sativus L.); ‘Acorn Squash’ winter squash (Cucurbita maxima Duchesne); ‘Connecticut Field’ pumpkin (Cucurbita pepo var. pepo L.); ‘Black Beauty’ and ‘Yellow Crookneck’ summer squash ; and ‘Hale’s Best’ cantaloupe (Cucumis melo L.). Approximately 120 seeds of each were placed into a petri dish containing 100% Admire 2E. After 10 min, seeds were removed and dried overnight on paper toweling. The following day, 21 June 2004, seeds were hand planted at the University of Arkansas Main Experimental Station, Fayetteville, AR. Seeds were spaced two feet apart in a single row. Plots were 60 ft long and row spacing was 3 ft. Experimental design was randomized complete block with 4 replications. Phytotoxicity was assessed at weekly intervals for 6 weeks by visually inspecting each of 25 plants in each plot.

Soil Application Results 2002

Five insecticide treatments were applied at planting and each resulted in a significant increase in the mean number of dead striped cucumber beetles and total dead beetles when compared to non-treated plots at 17 days after planting (Table 1). Although the number of dead spotted cucumber beetles was only significantly greater in plots receiving thiamethoxam, numbers were low. Also, all treatments applied at planting significantly reduced the level of foliar damage. At 23 days after planting, the mean number of dead striped cucumber beetles ranged from 0 in the check to 2.4 for the split application of thiamethoxam, i.e., 0.06 lb a.i./acre at both planting and at the two true leaf stage. Although numbers of each beetle species varied somewhat, all treatments except the low thiamethoxam rate at planting, significantly increased the number of total dead beetles. The addition of the second application at the two true leaf stage was of little benefit with imidacloprid. When the two imidacloprid treatments, i.e., 0.25 lb a.i./acre at planting versus the two 0.125 lb a.i./acre applications, were compared, no significant differences in the number of dead beetles were detected. However, with thiamethoxam the mean number of dead striped, spotted, and total beetles were significantly greater for the double treatments.

Table 1. Effects of soil applied insecticides on striped (STCB) and spotted (SPCB) cucumber beetles on zucchini, 2002.

Although the principal objective of the 2002 study was to determine the effectiveness of the soil applications for protecting squash seedlings, weekly samples were taken from plots receiving the high rates of imidacloprid and thiamethoxam and from non-treated plots through 56 days after planting to determine the length of toxicity to cucumber beetles (Table 1). In plots receiving imidacloprid (0.25 lb a.i./acre) at planting, the mean number of dead cucumber beetles was significantly greater than in non-treated plots at both the 39- and 56-day sample periods. The likely reason for the continued increase in the number of dead beetles is related to the increase in plant size. At 56 days after planting, plants were larger and had more time to attract beetles. The number of dead cucumber beetles in plots receiving thiamethoxam was more variable. However, thiamethoxam toxicity was still evident 56 days after planting when the mean number of dead cucumber beetles in plots receiving the 0.125 lb a.i./acre rate was 13.5.

Soil Application Results 2003

Similar results were obtained during the 2003 soil treatment study (Table 2). At 14 days after planting, significantly more dead striped, spotted, and total cucumber beetles were counted in plots receiving imidacloprid when compared to non-treated plots. Significantly more dead striped cucumber beetles also were observed in plots receiving thiamethoxam or dinotefuran. Foliar damage ratings were significantly lower for all insecticides when compared to that in non-treated plots. At 24 days after planting, each of the insecticide treatments significantly increased the number of dead striped cucumber beetles and total beetles when compared to those in non-treated plots. Application of each insecticide also resulted in significantly lower levels of foliar damage from cucumber beetle feeding.

Table 2. Effects of soil applied insecticides on striped (STCB) and spotted (SPCB) cucumber beetles on zucchini, 2003.

Seed Treatment Results 2004

Dead beetle counts were not taken during the 11-day-after-planting sample because of heavy rain that occurred the previous night. Foliar damage ratings ranged from 2.4 for non-treated seeds to 0.1 for seeds dipped in 0.086% imidacloprid (Table 3). Significant reductions in foliar damage ratings were detected for all seed treatments. At 14 days after planting, significantly greater numbers of dead spotted cucumber beetles were observed in plots with seeds treated with the two highest levels of imidacloprid. Although foliar damage ratings were again significantly lower for all seed treatments when compared to non-treated seed, the two highest levels of imidacloprid (0.043 and 0.086% a.i.) were significantly lower than other seed treatments. At 23 days after planting, only the two highest levels of imidacloprid treated seeds produced significant increases in numbers of dead beetles over those for non-treated seeds. These two treatments also had the lowest foliar damage ratings.

No symptoms of phytotoxicity were observed on any of the seven tested cucurbit cultivars from plant emergence until the end of the test six weeks after planting.

Table 3. Effects of imidacloprid seed treatments on striped (STCB) and spotted (SPCB) cucumber beetles on zucchini, 2004.

Conclusions and Recommendations

Each of the three tested neonicotinoid insecticides was effective against cucumber beetles when applied to the soil at planting. This was evident in increases of dead beetles in treated plots and in reductions of foliar damage. Iimidacloprid and thiamethoxam also were effective when applied into soil after plants had emerged and had developed two true leaves. However, substantial foliar damage was not prevented with the later applications. Had cucumber beetle populations been greater, it is unlikely that the delayed application could have prevented substantial plant mortality. The use of imidacloprid as a seed treatment was also effective against the cucumber beetle complex and resulted in increased levels of beetle mortality and reductions in foliar feeding. Seed treatments also reduced the amount of insecticide per acre and reduced the costs of chemical and application. Although concern with unwarranted insecticide use always exists with preventative applications at planting, historically, cucumber beetle populations are highly predictable in certain locations like the Arkansas River Valley in Arkansas and southwestern Missouri. In these areas, it is likely that the preventative insecticide applications for cucumber beetle management on cucurbits are justified and offer the cucurbit producer a viable alternative to multiple foliar sprays.

Literature Cited

1. McLeod, P. 2006. Identification, biology and management of insects attacking vegetables in Arkansas. Sirena Press, Santa Cruz, Bolivia.

8. Thomson, W. T. 2000. Agricultural Chemicals – Book I: Insecticides, Acaracides and Ovicides. Thomson Publications, Fresno, CA.

Controlling Cucumber Beetles – How To Deter Cucumber Beetles In The Garden

Controlling cucumber beetles is important for your garden if you grow cucumbers, melons or squash. Damage from cucumber beetles can devastate these plants, but with a little cucumber beetle control, you can keep this harmful pests from destroying your cucumber and cucurbit crops.

Cucumber Beetle Identification

Cucumber beetles actually come in two varieties. While the two varieties look different, their damage is the same.

The striped cucumber beetle is either yellowish-green or orangeish-green with three black stripes down its back. The spotted cucumber beetle is also either yellowish-green or orangeish-green with 12 black spots on its back. Both pests are about 1/4 inch long.

Cucumber Beetle Damage

Image by carol2chat Cucumber beetles will eat the leaves, flowers and fruit of beans, cucumbers, melons, asparagus, corn, eggplant and squash plants and their larva will chew on the roots of these plant. While there is some damage from this to the plants, the real reason that cucumber beetle control is important to a garden is because cucumber beetles are carriers of cucumber bacterial wilt and cucumber mosaic, which affects squash, melons and cucumbers. They affect cucumbers the most.

Cucumber bacterial wilt and cucumber mosaic can survive in the digestive system of a cucumber beetle and as a cucumber beetle moves from plant to plant to feed, it spreads these diseases to all the plants it eats. Once a plant is infected with either bacterial wilt or cucumber mosaic, it cannot be cured and will either die or become unproductive after they are infected.

How to Deter Cucumber Beetles

Controlling cucumber beetles starts with keeping them away from your plants in the first place. The best way how to deter cucumber beetles is with row covers or some other covering on the plant. Cucumber beetles will emerge in mid spring, so row covers should be in place as soon as the plants are put in the ground to protect them from the cucumber beetles. The row covers can be removed when the plants bloom in order to allow pollinators access to the plants.

How to Kill Cucumber Beetles

Since cucumber beetles overwinter in wood and are difficult to eliminate through simple garden cleanliness, simply deterring cucumber beetles may not be an option if your garden is already infested with these pests.

One method of cucumber beetle control is to use insect predators. Natural predators to cucumber beetles include:

  • Soldier beetles
  • Tachinid flies
  • Ground beetles
  • Entomopathogenic nematodes
  • Braconid wasps

Insecticides can also be used for controlling cucumber beetles as well, but keep in mind when you use insecticide, you may kill the natural predators and beneficial bugs that are already in your garden. Using insecticide to kill cucumber beetles is a multi-step process to ensure that both the adult and larvae of cucumber beetles are killed. In all steps, the best time to treat your plants with insecticide is in the early evening as this is when the cucumber beetles will be most active.

Cucumber beetle control with insecticide starts in mid spring when the cucumber beetles emerge from their overwintering locations. Spray the plants weekly for two to three weeks. Treat the plants again in early summer so that you can kill some of the cucumber beetle larvae that will be emerging from the eggs at this time. Treat your plants again with insecticide in the late summer to kill any adults that have recently developed from the larvae.

The last thing you want to see in your yard is a cucumber beetle.

No, really, I’m not kidding. If you are starting to see these little beetles scattered around your garden, that is a major problem. The larvae have a tendency to gnaw on the roots of your plants, and the adults chew on the foliage. Even worse, they spread plant disease.

So what can you do to eliminate the spread of cucumber beetles? I’ll tell you how to get rid of cucumber beetles. I’ll also help you learn everything you need to know about the myriad of beetles that are called cucumber beetle, and how to prevent them from becoming a permanent problem.

Organic Products To Eliminate Cucumber Beetles:

  • Safer Brand Yard and Garden Spray
  • Take Down Garden Spray
  • PyGanic
  • Monterey Garden Insect Spray

Environmental Products To Eliminate Cucumber Beetles:

  • Ladybugs
  • Lacewings
  • Beneficial Nematodes
  • VivaTrap Cucumber Beetle Trap

Cucumber Beetle Preventative Options:

  • Surround WP
  • Harvest-Guard Floating Row Covers

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Cucumber Beetle Overview

Common Name(s) Cucumber beetle, Western corn rootworm, Spotted cucumber beetle, Southern corn rootworm, Western cucumber beetle, Western spotted cucumber beetle, Curcubit beetle, Vaquita de San Antonio, Banded cucumber beetle, Northern corn rootworm, Striped cucumber beetle, Western striped cucumber beetle
Scientific Name(s) Diabrotica virgifera virgifera, Diabrotica undecimpunctata, Diabrotica speciosa, Diabrotica balteata, Diabrotica barberi, Acalymma vittatum, Acalymma trivittatum
Family Chrysomelidae
Origin Various, depending on species
Plants Affected Cucumber, cantaloupe, squash, gourd, pumpkin, corn, soybean, cotton, beans, potato, grape, sweet potato, tomato, cassava, rice, sorghum, wheat, cabbage, amaranth, peanut, watermelon, bell pepper, mulberry, pea, beet, okra, onion, lettuce, oats
Common Remedies Pyrethrin and spinosad sprays, ladybugs, lacewings, spined soldier bugs, beneficial nematodes, pheromone lures, trap crops, floating row covers, kaolin clay dusting

Types of Cucumber Beetle

The cucumber beetle falls into two separate insect genera, the Diabrotica and Acalymma. Both are part of the Chrysomelidae family of insects, which encompasses many of the beetle species. While there’s a number of different species in each genera, we’re going to focus on common food pests.

One thing to be aware of is that nearly all types of cucumber beetles can transmit plant diseases. The most commonly-spread are bacterial wilt and the cucumber mosaic virus. So it’s essential to get rid of these before they eat or poison your plants!

Diabrotica virgifera, ‘Western Corn Rootworm’, ‘Mexican Corn Rootworm’

Diabrotica virgifera. Source: Marco Spiller

There are two subspecies of this insect, Diabrotica virgifera virgifera (the Western corn rootworm) and Diabrotica virgifera zeae (the Mexican corn rootworm). The two are so closely related that it’s incredibly hard to tell them apart except by location.

In its larval form as the western corn rootworm, Diabrotica virgifera is one of the most destructive insects to corn crops in the U.S. It ranges from the southwestern edges of the “corn belt” all the way to the eastern coast. It also has spread to and throughout Europe, causing major issues in a number of countries there.

As an adult, Diabrotica vergifera is still quite damaging in that it continues to spread its species, and so it should be killed quickly once identified. Keep an eye out for this black and yellow beetle and strike back quickly!

Diabrotica undecimpunctata, ‘Spotted Cucumber Beetle’, ‘Southern Corn Rootworm’, ‘Western Cucumber Beetle’, ‘Western Spotted Cucumber Beetle’

Diabrotica undecimpunctata. Source: judygva

This species also has multiple subspecies classifications. Those are:

  • Diabrotica undecimpunctata howardi (the spotted cucumber beetle or southern corn rootworm)
  • Diabrotica undecimpunctata undecimpunctata (the western spotted cucumber beetle)
  • Diabrotica undecimpunctata tenella (the western cucumber beetle)

These are also major agricultural pests and should be destroyed quickly. These impact a wider variety of crops than the western corn rootworm does. These can be problematic on a number of cucurbits, beans, and more.

One thing that all three subspecies has in common is their coloration. This yellow beetle with black spots may have a different number or placement of their spots, but otherwise they’re similar in their looks.

Diabrotica speciosa, ‘Cucurbit Beetle’, ‘Vaquita de San Antonio’

Diabrotica speciosa. Source: jarbas mattos

Known in South America as vaquita de San Antonio. The cucurbit beetle not only feasts on cucurbits but on beans, grapes, and potatoes too. It’s primarily located in and around South America, and is a major agricultural pest in that region. While it’s prettier than some of the other cucumber beetle types, it can be quite destructive.

Diabrotica balteata, ‘Banded Cucumber Beetle’, ‘Belted Cucumber Beetle’

Diabrotica balteata. Source: Sean McCann

The banded cucumber beetle is spread from the United States all the way south to Colombia and Venezuela. It has an extremely wide range of foodstuff. Some foods are cucurbits such as cucumber, melons, squash, and gourds. It also eats some cruciferous vegetables like cabbage, some nightshades such as tomato and potato, and more.

This cucumber beetle is not as prominent in the northern United States as the weather there is simply too cold for it to thrive. However, in the southern half it’s become relatively widespread since its appearance in the late 1920’s.

Diabrotica barberi, ‘Northern Corn Rootworm’

Diabrotica barberi. Source: Keith Roragen

Found primarily in the U.S. and Canada, the Northern corn rootworm is just as dangerous in the cooler climates as the Southern corn rootworm is in warmer ones. This little insect has just as wide of a food preference as its southern relative, and is equally dangerous in the garden.

Acalymma vittatum, ‘Striped Cucumber Beetle’

Acalymma vittatum. Source: Jesse Christopherson

In the other genus which comprises the cucumber beetle population, we have the striped cucumber beetle. This is a severe pest for crops in both larval and adult phases of life. It feeds primarily on cucurbits. .The adult form prefers older plant foliage. The larvae attack the root structure of the plants from within the soil. This cucumber beetle is primarily found in North America, specifically the central and eastern portions of the United States.

Acalymma trivittatum, ‘Western Striped Cucumber Beetle’

Acalymma trivittatum. Source: loarie

This close relative of the striped cucumber beetle is a variation which tends to stay west of the rest of its family. It has lots of similarities in terms of food crops. This might have been an evolution that prefers the hotter western climates.

Life Cycle of Cucumber Beetles

Cucumber beetle laying egg. Source: DrPhotoMoto

Adult cucumber beetles mate when they are roughly a week in age. Roughly two weeks later, the female of the species will begin to lay eggs.

Depending on the species, cucumber beetles lay eggs in a variety of places. Generally, they prefer either the underside of leaves or flower petals for their laying area. Some species lay in large clusters every few days. Others opt to lay a few eggs every day.

When the eggs hatch, larvae emerge. These rootworms are tiny initially, but grow to reach sizes of a quarter to a half inch in length. Growth happens in a series of larval cycles called instars, and there are 3-4 of them for most species. Once emerged, the larvae will tunnel into the soil at the base of their plant to attack the roots. This gives them some protection as they feed from any predators which might otherwise eat the larvae.

Once the larvae have grown over a period of a few weeks, they will pupate in the soil. When pupation has concluded, the adult will emerge and begin the cucumber beetle life cycle anew.

Common Habitats for Cucumber Beetle

Adult cucumber beetles are able to travel for short distances, and can slowly migrate throughout an area. Once a cucumber beetle has found their ideal home, they tend to stay there for a while. Typically, this home is in an area where there is a plentiful supply of their preferred foodstuff.

Different beetles inhabit different areas depending on their species. Some species are incapable of overwintering (usually the warmer-climate species), but there’s a few cold-weather varieties that do. These enter a state of diapause in compost piles or under soil. That’s almost like a state of suspended animation. Once warmer weather has returned, the adults emerge to continue life as normal.

What Do Cucumber Beetles Eat?

Other than the obvious cucumbers which they’re named after, cucumber beetles tend to be fond of cucurbits and corn as their primary crops. However, depending on the variety, the following plants may be impacted:

Obviously, it’s important to eliminate these as fast as you spot them. Right now, you’re probably asking how to get rid of cucumber beetle infestations in your garden. Read on as I tell you not only how to kill cucumber beetles, but how to make your garden less of a target!

There are a variety of pyrethrin options that have an effect against some varieties of cucumber beetles, with varying levels of efficiency.

Start out with something such as Safer Brand Yard and Garden Spray, which is a blend of pyrethrin with potassium salts of fatty acids. This is a good overall solution, and is also effective against leafhoppers, asparagus beetles, tomato hornworms and more.

If that doesn’t work, you can move on to Take Down Garden Spray, which is a blend of pyrethrin and canola oil. Oils tend to deter pests from taking up residence in your plants. They have the added bonus of smothering any eggs which are already in place. The oils also break down slower, which protects your plants longer. Take Down is also an effective miticide if you’re having problems with spider mites. It also works against the host of other insects mentioned above.

Finally, if you want to give pyrethrins one more shot before moving onto something else, you can go for a strong solution of PyGanic, a pure pyrethrin spray option. Just blend it at the highest maximum recommendation on the label for your types of plants.

Some cucumber beetles are resistant to pyrethrins, so it’s good to have an alternative. In this case, I would recommend a spinosad spray. Monterey Garden Insect Spray is a solid choice.

Cucumber beetles are notorious for being difficult to control with insecticidal options. If none of these work, concentrate on environmental and preventative options. But if they appear despite all of your other efforts, strike quickly to keep them from breeding!

Environmental Cucumber Beetle Control

Your first stage in environmental control should always be to encourage beneficial insects that prey on your pests.

To do this, you’ll want to plant flowers or herbs that encourage ladybugs and lacewings to stick around your yard. These two insects will happily consume the eggs of cucumber beetles. They’ll also eat any newly-hatched larvae they might encounter.

Another beneficial insect for your arsenal is the spined soldier bug, which will quite happily suck the life out of cucumber beetles. I mean that quite literally. Spined soldier bugs have a sharp spear-like proboscis that they will jab into garden pests to feed on bug juices. In addition, spined soldier bugs are quite useful against a whole host of other pests. They’ll happily eat your cucumber beetles, but they’ll also eat cabbage loopers, flea beetles, cabbage worms, and many more.

Don’t neglect to add a protective force to your soil as well. Beneficial nematodes will attack larvae that might get under the surface of the soil, killing them quite effectively. A healthy population of beneficial nematodes in your garden beds will eliminate most pest larvae.

If the beneficial insects aren’t working, try planting some trap crops. These should be plants that cucumber beetles are especially fond of. You will be effectively sacrificing these plants for the chance to kill the beetles, so don’t expect to get much of a harvest from them. When the beetles start showing up on those plants, hit them with an insecticide option to wipe them out fast.

Speaking of traps, if you’re in the western US, you may have some good results from commercial lure traps. The VivaTrap Cucumber Beetle Trap uses a pheromone lure that attracts many of the cucumber beetle varieties in the western United States, paired up with a sticky trap that the pests can’t escape from.

Preventing Cucumber Beetles

Before you plant, look for specific plant varieties that are resistant to cucumber beetles. If you already know that there’s cucumber beetles in your area, you might as well try those varieties. But realistically, your best bet is to keep them from ever reaching your plants in the first place!

Treat your plants to a dusting of kaolin clay. This superfine clay leaves a film behind on the leaves of plants which insects don’t like to lay eggs on or eat. I recommend Surround WP, a commercially-available source of kaolin clay that’s meant for use on plants.

Using floating row covers, such as Harvest-Guard, works extremely well to keep adult beetles from reaching your plants. If they can’t get to the plants, they can’t lay eggs on them! You will either need to hand-pollinate your plants or remove the row covers when they flower. Otherwise, bees won’t be able to reach the plants either.

There has been some research into using vermicompost as fertilizer instead of using more traditional slow-release chemical fertilizers. So far, it’s showing that the striped cucumber beetle is less likely to strike plants grown in a vermicompost-rich plot. Researchers believe that this may be resulting from an increase in phenolic compounds in plants grown with vermicompost. Since vermicompost is a great option as a fertilizer, it certainly can’t hurt to try it!

Frequently Asked Questions

Q: These beetles just aren’t going away, no matter what I do.

A: There are some varieties of cucumber beetles that are stubbornly determined to live, no matter what you do. The striped cucumber beetle is among those. It tends to be resistant to a lot of organic measures. In those situations, it’s best if you do some trap crops to try to lure the beetles to those. Then, hit those plants with a more potent chemical insecticide when they show signs of cucumber beetle damage.

Other than that, hand pick and dispose of any beetles you find. Also, make sure you hang VivaTraps or other commercial sticky traps around your plants to catch the ones you don’t get.

Q: Is there anything else that I can try that you haven’t mentioned yet?

A: There is one last option, but it’s only really useful in areas with a long growing season. You can do a delayed planting for anything the cucumber beetles in your area are most likely to eat. Wait until after the first burst of cucumber beetles would normally emerge after overwintering. Once the adults have moved on to better grazing areas, plant your plants. Place floating row covers over them when you plant to prevent their return.

You may need to hand-pollinate your plants if using this method. But this may be the best chance to be sure there aren’t any beetles lurking beneath your row covers.

Nobody wants pests to eat their plants, and the cucumber beetle’s a nasty one! Have you battled this beetle? What did you find effective? Share your helpful hints in the comments below!

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How to Control Cucumber Beetles Organically

Cucumber beetles may seem to be a small problem- after all they can’t fall a plant in hours like the squash bug can- but cucumber beetles can actually be bad news for your garden!

Cucumber beetles are small yellow and black beetles that are either spotted or striped (more on that in a minute!). They are only about 1/4 of a inch long, and more of an oval shape than the round shell of a ladybug.

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The larva and adults can feed on the roots, leaves, and fruits of plants in the cucurbit family (cucumbers, melons, squash, pumpkins). Most of the time these beetles will not kill your plant- but there is a hidden danger when it comes to cucumber beetles- they carry diseases. And these diseases can harm, or even kill, your plants.

Striped Cucumber Beetles vs. Spotted Cucumber Beetles

There are 2 types of cucumber beetles. The striped cucumber beetle and the spotted cucumber beetle. You can probably tell them apart by their names alone- both are yellow but the striped one has black stripes down their back, and the spotted one has rows of black spots.

Spotted cucumber beetles aren’t as picky when it comes to their diet and will feed on a variety of plants. The striped cucumber beetle tends to stick to the cucurbit family and rarely will feed outside of this group of plants.

Striped cucumber beetles lay their eggs at the base of the plants- which means that the roots suffer the most damage from the larva.

Both types will feed on the plants causing stunted growth, less fruit, and disease like bacterial wilt.

5 Ways to Control Cucumber Beetles Naturally

Companion Planting

There are few different plants you can try to interplant with your cucumbers to repel the cucumber beetle. These include flowers such as nasturtium and marigold. Or vegetables like radishes and corn.

You can read more on the best plants to plant with your cucumbers, and what not to plant, on my article The Best Companion Plants for Cucumbers in the Backyard Garden

? In a Hurry? Get Started With Companion Planting Right NOW!
Pick up a copy of my Companion Planting Guide and Binder to help you design the perfect garden beds with companion planting in mind. Everything you need to know about companion planting in an easy to read format so you can start companion planting sooner!

Timing

Your timing can go along way in how many pests you deal with in your garden. Learning the lifecycle of a particular pest can help you decided when the best planting time is for your area.

When it comes to cucumber beetles, many times plants that are planted in the fall and spring do better than ones planted in the middle of the growing season.

Also, instead of planting seed directly in the ground, start your cucumbers in pot. Cucumber beetles attack small, weak plants, so transplanting larger, strong plants into the garden will give your cucurbits a strong start.

Other bugs can be your best friend when it comes to fighting garden pests like the cucumber beetle. There are quite a lot of beneficial insects that can help you in your fight to control cucumber beetles. These include the tachinid fly and braconid parasitoid wasp. both of which are parasites of the cucumber beetle. They will lay their eggs on the host and their larva hatch and eat the cucumber beetles.

Ground beetles can also feed on cucumber beetles- so don’t squash those!

And if you are scared of spiders, be sure to leave the wolf spider alone! They can give a good deal of help in getting rid of cucumber beetles- plus the cucumber beetles tend to steer clear of areas that have a lot of wold spiders.

Insect eating nematodes can help fight cucumber beetles (and fleas!) so you can add them to your arsenal as well. You can even buy them on Amazon!

Related Reading: How to Get Rid of These Common Garden Pests Naturally!

Traps

Yellow sticky traps can help control the number of adult cucumber beetles in your garden. The cucumber beetles are drawn to the color yellow so simply hang the traps around your plants and they will fly onto them and stick.

Hand picking isn’t at all effective for trapping cucumber beetles- they are quick flying little things! But you can try vacuuming or otherwise sucking up the beetles on your plants if you only have a small area to cover.

Row Covers

Floating row covers, especially on early, young plants, can do a lot towards protecting your cucurbit plants. You cover the plants until they begin to flower, giving them a very long head start in getting strong enough to fight off cucumber beetles.

Just don’t forget to remove the covers at flowering- the pollinators need access to the plants or you won’t get any fruits!

More Tips on Handling Cucumber Beetles in the Organic Garden

Mulch

Mulch can help control cucumber beetles in a few different way.

Many mulches, like straw or wood, is the perfect habitat for wolf spiders. And I already talked about why you want wolf spiders!

Organic mulches that are high in organic matter and microorganism makes for stronger plants and the cucumber beetles will be less likely to hangout in your garden.

Plastic mulch, especially ones that are reflective can also repel cucumber beetles.

Resistant Varieties/ Trap Crops

You can also try planting resistant varieties of cucurbits. For example, cucumber beetles don’t like burpless cucumber as much as other types. They also tend to prefer zucchini-type squashes over others.

It’s also important to choose varieties that are also somewhat resistant to the bacterial wilt carried by the cucumber beetles.

Some varieties to try are: blue hubbard squash, white bush squash, Waltham butternut, chinese long cucumbers and black beauty zucchini.

Crop Rotation

Because cucumber beetles overwinter in the soil where the previous year’s crop was planted, crop rotation can help control the cucumber beetles in your garden. Moving your cucurbits to a new location will prevent newly hatched larva from attacking the roots of the new year’s plants.

The farther distance you can put between last year’s and this year’s crop the better. Of course, cucumber beetles are highly mobile and will fly to your new planting area, but crop rotation reduces the larva damage and combined with all of the other tips, is just one more step to controlling cucumber beetles in your garden.

More About Cucumbers:

7 Tips to Growing the Best Cucumbers

10 Ways to Preserve Cucumbers

5 Ways to Trellis Your Cucumber Plants

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