Spider mite on plants

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How To Get Rid Of Spider Mites On Houseplants

by Madison Crabtree August 27, 2019

From a distance, your houseplant with browning leaves might just look a little parched… but take a closer look, hold the plant up to the light and look under the leaves – if you see delicate webbing and tiny little dots moving around, you’ve got a case of spider mites on your hands!

Symptoms

Let’s take a look at how you can spot these pests. The first thing you’re likely to notice is patterns of silvery dots or stippling on the leaves of your plant. Looking closer, you will see small, delicate webs in corners of stems or underneath leaves with what look like tiny white dots scattered throughout. Those are spider mites! It’s hard to see them until their population explodes, and be aware that spider mites also come in brown and red. Other signs of their damage are brown spots and holes in leaves where these pesky critters have chewed straight through.

Spider mites are difficult to see with the naked eye, but adults have eight legs and little oval bodies and can come in a variety of colors. Sometimes called webspinning mites, these pests are particularly pesky because of their ability to double their population every couple of weeks. It takes a spider mite just a week to become full grown, and a couple more weeks to lay hundreds of eggs on the undersides of leaves. They breed quickly in warm, dry conditions and can be a bigger problem in the winter when your heating system runs and dries out the air.

Where do they come from? Spider mites are wind surfers that range over wide areas by riding their webbing on the breeze. Their mobility and extremely small size makes it easy for them to arrive unnoticed, even through screens on windows and doors.

Diagnosis

Spider mites feed off of materials from plant cells, and as they continue to damage your plant, leaves will become speckled, wilt, turn brown or yellow, and fall off. The spider mites target the ‘stomata’ of leaves – kind of like pores that regulate water retention in different environments – making it vulnerable to water loss. Eventually, when enough leaves shrivel up and fall from the plant, the plant can weaken and die. It’s possible to quell a spider mite problem, but it will require dedication.

Ready to take on the challenge to save your plants? Read on for prevention and treatment methods!

Prevention

1. CLEAN THOSE LEAVES

Spider mites like dusty leaves on plants that are suffering from water stress. A good way to discourage them is by wiping dirty leaves periodically and making sure your watering schedule is right for your plant. You can also try using a leaf shine periodically.

2. KEEP HUMIDITY UP

Since spider mites like it dry, keeping the air humid around your plants is a great way to deter them from settling on your plant. Use a humidifier for the room, periodically spray a fine mist on your plants, or leave a container of water to evaporate nearby. You can also try adding peat moss to your soil and making sure your plant isn’t in direct sunlight by using a sheer curtain.

3. DEBUG FOR DEPARTURE

If you like to keep plants outside during the summer, make sure to take precautions to debug your plants before bringing them back inside.

Treatment

Note: Make sure that spider mites are actually living on your plant before treating it. Often, colonies of mites are already gone before their damage is noticed. Try shaking some leaves you suspect of having spider mites over a sheet of plain white paper to check for little crawlies, which will show up as little moving spots, or looking closely at webbing for movement.

1. PRUNE & ISOLATE

The first thing you should do when you discover spider mites is to isolate the plant away from other plants. You can try to prune out sections with visible webbing, disposing of them immediately & carefully. Then, use one or more of the methods below to treat the rest of the plant. Remember to clean and disinfect the area that the plant was in before you moved it, as well as your hands afterwards.

2. SPRAY WITH PLANT-BASED MITICIDES

Pick up some commercially available miticides that use natural ingredients to get the job done, leaving the plant unharmed. Make sure to test your spray on a leaf first before spraying the entire plant. Pro Tip: Every once in a while, mix up the product you’re spraying so that the spider mites won’t build up an immunity to it. Here’s a quick list of effective sprays:

  • Pyrethrum: Derived from a relative of the chrysanthemum, this miticide is the best to begin with. Some mite species can develop a resistance to it, so keep an eye on your plant after spraying.
  • Cinnamite: This pesticide is derived from cinnamon oil and is non-hazardous. It won’t kill eggs, but it is effective for killing adult spider mites. Spray this one on your plant every 3 days over a couple of weeks to make sure you get all of them!
  • Neem oil: Neem oil is an effective treatment for all kinds of pests. It’s derived from the nuts of the Neem evergreen tree and will not only treat the problem you’re having right now, but also provide some repellant for new critters after. You’ll have to regularly re-apply neem oil as it takes a while to become effective.
  • Rosemary oil: You will need to dilute rosemary oil with water, but it can be an effective treatment for spider mites, especially for herbs and plants you want to harvest and eat later, as it is non-toxic to humans.

3. MAKE YOUR OWN HERBAL TEA MITICIDE

This tea is to die for. Mix 1 tablespoon ground cinnamon, 1 tablespoon ground cloves, and 2 tablespoons of Italian seasoning in a quart of water. Boil the water, then take off the heat. Once it’s cooled slightly, add 2 tablespoons of crushed fresh garlic. Rest until cool, then strain. Now, with your mixture, add a splash of dish soap and pour into a spray pottle. Shake well and spray the underside of the leaves with your DIY miticide every 3 days for a couple weeks!

4. PUT HOUSEHOLD CHEMICALS TO GOOD USE

If you don’t want to go out and get any fancy miticides or create your own, you can easily make use of what you have in the medicine cabinet or your kitchen at home:

  • Rubbing alcohol: Mix rubbing alcohol with water to spray onto your plant, or use it to manually wipe off leaves. For sensitive plants, try 1 part alcohol to 3 parts water, and for hardier plants, try a 1 to 1 mixture.
  • Dish soap solution: Using a mixture of 1 liter of warm water and 1 teaspoon of liquid dish soap, either mix the solution well in a spray bottle, or mix it into a bucket and wash the plant with a cloth or sponge. Re-apply regularly for best results.

5. MIGHTY MITES

Don’t want to deal with re-applying sprays regularly? Here’s a one-step solution that, while it might freak some plant parents out, is a foolproof method for getting rid of spider mites: you can purchase predatory mites that feed on spider mites, release them onto your plant, and let them take care of the rest. One type of predatory mites that works for this is Phytoseiulus persimilis. You can also employ ladybugs, lacewing, and others to get the job done.

Note: If you go this route, avoid miticides and pesticides that might harm the good mites as well as the bad ones! Rosemary oil won’t harm the good mites, so try that instead.

6. GIVE YOUR PLANT A SHOWER

One way to fight mites is to regularly hose down your plant with a handheld shower nozzle using room temperature water, paying close attention to the underside of leaves especially. When the mites are gone, continuing to give your plant a shower every once in a while can help prevent other pests from taking hold.

7. CONSIDER CUTTING YOUR LOSSES

No one wants to lose their favorite plants, but if those mites are still hanging on after you’ve tried everything, you might consider throwing out infested plants and starting anew after thoroughly cleaning the areas that they were in.

We hope these tips and tricks help you to eradicate these miniscule menaces once and for all! Good luck, plant fam!

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How to Kill Spider Mites on Plants

Spider mites are perhaps the most dreaded of house plant pests. By the time you notice their faint webbing, the plant is seriously infested.

Mites form colonies and multiply quickly. Most eggs are female and adult females lay about 100 eggs, with eggs hatching just 3 days after they’re laid. The whole lifecycle — from egg to egg-laying adult takes only 2 weeks. If not controlled, mites can destroy a plant and then move on to nearby plants.

What They Look Like

Often called “red spider mites”, they may be red, green, or yellow. Indoors, the most common is the two-spotted sider mite. But, you won’t notice their spots. Mites are specks about the size of pepper flakes. And they are true spiders, not insects.

They suck plant juices with their needle-sharp mouthparts. Attacks can cause leaves to look mottled and yellow, dusty, distorted, or dry out and drop off. Uncontrolled infestation can kill a plant.

Spider mites cause yellow speckled marks on foliage, as well as spider webs.

Where to Find Them

These eight-legged pests are so tiny, you need a magnifying glass to see them. You’ll likely notice their fine webbing first. Look for webbing on the undersides of leaves and between leaves. If you tap the leaf over a sheet of white paper, you may be able to see moving specks.

Spider mites love warm (70-80°F/21-27°C), dry conditions, making heated homes in winter an ideal environment for them to thrive.

Ivy is a favorite house plant for these bugs.

Prevent an Infestation

Raise humidity. Most house plants have tropical origins and appreciate regular misting to raise the humidity around them. Misting with tepid water not only adds moisture to the air, it also discourages spider mites because they love dry conditions.

Keep it clean. A big first step in spider mite control is to keep foliage clean. Wipe off dust regularly with a damp cloth. For fine-leafed plants — such as palms and ferns — use a fine spray of room-temperature water from a spray bottle. Your plants will love the extra humidity, but the mites won’t. Also clean gardening tools often to avoid giving pests a ride from plant to plant.

How to Kill Spider Mites on Plants

Isolate the plant and prune badly infested or damaged leaves.

Clean infested plants with a cloth or sponge dipped in soapy water. Use mild dishwashing liquid that doesn’t contain fragrance or other additives. Squirt 2 teaspoonfuls into 1 gallon of room-temperature water and gently wash the plant’s leaves, especially the undersides of leaves. Rinse well.

To wash the long stems of ivy, make a sinkful of soapy, room-temperature water. Swish the ivy stems through it with your hand for several minutes, then rinse thoroughly in clear room-temperature water. This should destroy any mites on the plant. Repeat in 2-3 days if necessary.

For heavy infestations, spray plant with an Insecticidal Soap made for indoor plants. Spray every 2-3 days to break the life cycle. It may take several applications. Make sure your plant is listed on the product label. Read the label carefully and follow the manufacturer’s directions for use.

Neem oil works great. It’s proven to kill these pests and their eggs. It’s an organic insecticide that’s safe to use on indoor plants.

Increasing the humidity around your plant may help to prevent another invasion.

  1. Home
  2. Pests and Diseases

Spider Mites – Trees and Shrubs

For mites on vegetables go to, Spider Mites on Vegetables
For mites on houseplants go to, Spider Mites – Houseplants

Closeup of spruce spider mite

Mites are not insects but are related to ticks and spiders. Adult mites have one sac-like body region, lack a distinct head, and have 8 legs. Spider mites feed only on plants and are very small, about the size of a period on this page. There are many different species of spider mites and are various colors. For example, the two-spotted spider mite is light yellowish-green with 2 black spots, and the spruce spider mite is grayish brown.

Mites on Evergreens


Hemlock mite damage


Hemlock rust mites

Webbing from high mite population Close-up of mite feeding damage on needles

Mite eggs on hemlock

Additional photos:


This type of damage is called ‘stippling’


Spider mite eggs


Spider mites on boxwood. Credit John A Davidson


Shed mite skins – Photo credit JA Davidson UMES

Life Cycle and Description

Spider mites develop through 5 stages from egg to adult. In hot weather, the generation time may be as short as one week. There may be up to 20 generations in a year depending on the weather. During hot summer weather, female two-spotted spider mites live about 30 days and produce about 100 eggs. This is why spider mite populations often build up so rapidly. Spider mite activity can occur any time after plants leaf out in the spring until early fall. The spruce spider mite attacks many conifers, especially dwarf Alberta spruce. Unlike other mites, it prefers cooler temperatures in early spring and late fall, and this is the best time to control them.

Most species of spider mites overwinter as white, brown, or red eggs. The two-spotted spider mite, which is the most common spider mite species, overwinters as orange adult females that hide in bark crevices.

Damage

As spider mites feed they suck out the green chlorophyll in leaves. The result of this feeding appears as minute white dots or flecks called “stipples”. Heavy mite feeding causes yellowing, browning of leaves, and eventual leaf death. During feeding, some mite species may inject toxins that cause varying degrees of leaf discoloration and distortion. Some spider mite species may produce webbing that covers leaves and stems when populations are high.The two-spotted spider mite feeds mainly on the undersides of the leaves.

Spruce spider mite

Damage appears as tiny yellow stipples on needles. The needles turn yellow, and then brown. The damage is usually first observed on the older needles at the base (or one side) of the tree (or shrub), eventually moving up the tree (or shrub). When the mite population is very high, webbing may be noticed on the needles. Lower branches may lose all of their needles, except new growth on spruce. Small trees and shrubs may be killed and large trees may have some dieback. This spider mite prefers cooler temperatures and is active in the spring (March – June) and fall (September – November).

Spider mites are very tiny, about 2 mm. They have 8 legs and are yellowish green when young. When mature and fully fed they are grayish black, with a tan area behind the mouthparts. The eggs are circular and reddish brown. There are several generations a year and eggs overwinter on the bark and needles. This mite prefers spruce, pine, hemlock, and arborvitae, but will attack other conifers. To check for mites on an evergreen, tap branches over white paper and look for the dark slow moving mites. Also look for predator mites, which are fast moving, and tiny round, black ladybeetles that feed on the mites. If predator mites are found, spraying may not be necessary.

There are other species of mites that attack juniper. The damage is similar to spruce spider mites but occurs throughout the summer.

Management of spruce spider mite

Use a horticultural oil spray (do not use on blue spruce) at the first sign of mite activity and damage unless predators are obvious and mite populations are low.

Rust mites

Can cause yellowing and dropping of needles on hemlock, fir, spruce, yew golden larch and pines. These mites are eriophyid mites, which are very tiny. At 10X magnification, they are visible as light yellow, spindle-shaped forms with four legs. On hemlock, the hemlock rust mite feeds on the upper and lower surfaces of the needles. On pine, rust mites are usually found between the needles within the needle sheath.

Monitoring

During the growing season, landscape plants should be monitored every 1-2 weeks for evidence of spider mite damage. Because indoor temperatures are relatively high and constant, plants should be checked on a weekly basis. Examine both sides of leaves; use a magnifying lens if necessary. Signs of active mite infestations include various instars of mites, eggs, webbing, and stippling. If damage is visible, but no live mites are found check leaves or branches higher up on the plant. Mites generally work their way up a plant and often the best place is directly above where the damage is most noticeable. A simple technique for sampling, (especially conifers) is to tap a few terminals or leaves over a piece of white paper. Wait a few seconds and watch for movement. The mites may take a short time before they begin crawling on the paper.

Control

Non-chemical Control

Plants and small trees can be hosed down periodically with a strong spray of water. (The force of the water will depend on the plant.) Be sure to get good coverage of the lower surface of the leaves. On conifers, thoroughly wash down the entire plant.

Biological Control

There are several species of predatory mites available commercially. The predatory mites are usually shipped in containers with pollen for food. They are sprinkled on the plants that are infested with spider mites. The rates will vary with the species of predator purchased. Many garden supply catalogs and biological control businesses sell predatory mites. They will recommend release rates and the species best suited for your needs.

Chemical Control

Chemicals should always be considered as a last resort. Use them only if non-toxic methods have failed. Overspraying with insecticides can increase spider mite problems because beneficial insects are negatively impacted.

The following pesticides are preferred if they are labeled for the plants you want to spray: Safer Insecticidal Soap, Horticultural Oil (e.g. Sun Spray, Volck Oil, etc.). These materials are the safest to use and have the least impact on beneficial insects and mites. The only drawback is that they are short-lived and retreatment may be necessary. Acceptable control will depend on thorough coverage of infested plants, including upper and lower surfaces of leaves. Horticultural oils may also be used at a rate of 3-4%, during the dormant season to control overwintering forms of spider mites on bark. Do not use horticulture oil on blue spruce.

Additional Resource

(PDF) HG 13 Spider Mites

Pirone, P.P. 1978. Diseases & Pests of Ornamental Plants, 5th Ed. New York: John Wiley & Sons. 566 pp.

Olkowski, W., S. Daar, and H. Olkowski. 1991. Common-Sense Pest Control. Newtown, CT: The Taunton Press. 715 pp.

Mention of trade names in this publication does not constitute an endorsement by University of Maryland Extension

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Spider mites

How to get rid of mites

Webbing on a plant caused by spider mites Spider mite feeding damage Predatory mites can control spider mite populations ​ Velvet mite ​

Check plants regularly for spider mites

  • Examine plants for stippling and/or webbing.
  • Look closely with a hand lens on the underside of discolored leaves for the presence of spider mites.
  • You can also hold a white piece of paper or cardboard underneath potentially infested leaves; shake the leaves and look for spider mites that have fallen.
  • Check garden plants every 3-5 days, especially under drought conditions.

Watch plants for signs of stress

Spider mites thrive on plants under stress. Keep plants well watered to reduce the chances of a spider mite attack.

  • Most plants should receive about one inch of water a week to avoid stress conditions.
  • Conserve moisture through proper mulching.
  • Select drought tolerant plants for locations that are particularly hot and dry.
  • Do not fertilize plants during drought, as this can add further stress to plants.
  • Do not overwater as this can lead to root rot.

Use a high pressure water spray to dislodge some of the spider mites. This can also wash away their protective webbing.

Natural enemies like velvet mites can control spider mites

Certain species of lady beetles (e.g. Stethorus sp.) and predatory mites (e.g., Phytoseiulus persimilis) naturally control spider mite populations.

Velvet mites feed on spider mites

Velvet mites are 1/16 – 1/8 inch long and are found on the soil surface. They are active during spring.

  • Mite eggs and larvae can grow inside insects.
  • They are harmless to people and gardens.
  • Apart from spider mites, they can control other pests like, spring cankerworm, cabbage moth, lace bug and other arthropods.

If the spider mite population is high, natural enemies are not effective at controlling spider mites.

Using pesticides like carbaryl and imidacloprid for mite control can kill these natural enemies as well.

Using pesticides

Insecticidal soap and horticultural oil

These are effective against mites and have little impact on people, animals and nontarget insects.

These products will only kill mites that the pesticide directly contacts. They do not have any residual activity.

  • Target the underside of leaves as well as the top.

  • Repeat applications may be needed.

Pesticides

Effective active ingredients of residual pesticides include bifenthrin, deltamethrin and lambda cyhalothrin. Use these pesticides only when necessary, as they might affect a variety of insects.

Most spider mite infestations occur when it is hot and dry.

  • Water plants thoroughly before spraying pesticides for spider mites.

  • Spray in the early morning or early evening.

  • These steps will reduce the risk of further stressing plants and causing injury.

    CAUTION: Mention of a pesticide or use of a pesticide label is for educational purposes only. Always follow the pesticide label directions attached to the pesticide container you are using. Remember, the label is the law.

Spider mites, also referred to as web-spinning mites, infest home and agricultural areas around the world. They spin their webs on the stems and the underside of the leaves where they also lay dozens of eggs. This webbing makes it easy to identify an infestation and distinguish web-spinning mites from different mite species and other plant-damaging pests such as aphids.

How to Identify Spider Mites

Image of a Red Spider Mite on a leaf.

You might not see spider mites at first glance; however, if you look closer, you’ll notice tiny dots moving frantically over the leaf’s surface. Gazing through a magnifying glass reveals an entirely different picture and gives you a close-up look of these invasive pests at work. Numerous spider mite species live and thrive in backyard gardens and in greenhouses, and you can identify many of them by examining their body type, color and markings. Some of the most common spider mites include:

  • Two-spotted spider mites: These mites were once only native to Europe and Asia, but they have spread across the world in shipping containers. They range in color from dark red to green, which makes them even more difficult to see against the leaves. Under magnification, you can see two dark spots along their backs. Two-spotted spider mites have small, oval-shaped bodies and feast on everything from vegetables to flowers.
  • Southern red mites: Red mites have a red appearance and bulbous-shaped bodies. They mostly attack broadleaf plants and often invade shrubs and herb gardens. Red mites not only feast on the cell content within leaves but also on the fruit itself, creating even more havoc in agricultural crops. They thrive in cool weather during the spring and the fall and usually go dormant in the summer.
  • Spruce mites: These mites feed on needle-leaved conifers and cause massive damage in tree farms. As hatchlings, they appear lighter green in color and turn darker as they mature. Spruce mites also prefer cooler weather and lay their eggs at the base of the needles to survive the winter.

Other common spider mites include the European spider mite and the citrus mite. Regardless of the species, each of these mites threaten plants wherever they go. In small numbers, they cause insignificant damage to plants. However, these tiny arachnids can destroy entire crops and greenhouse plants without careful management and control.

The Spider Mite Life Cycle

Depending on the location, some spider mites can feed and reproduce throughout the entire year as long as the plants retain their leaves. In cooler areas where trees and plants drop their leaves, spider mites spend the winter under the bark or in ground litter. They return to feeding and reproducing once the weather permits and the leaves grow green and strong.

Spider mite development varies depending on the species, but each mite goes through similar life cycles. This cycle includes the egg, the larvae, two nymph stages and the final adult stage, and the entire development cycle can take anywhere from five to 20 days under ideal conditions. Female spider mites live between two and four weeks and can lay several hundred eggs during their lifetime.

The eggs, which are translucent and have a spherical shape, look like tiny water droplets against the leaves. As the spider mites develop inside the casing, the eggs transition from being translucent to having a cream color. The hatchlings then break out from the eggs and have only six legs; however, they develop all eight legs as they mature. The young feed on the underside of the leaves and continue to damage the plant as they develop into adults.

Spider Mites and the Damage They Cause

Severe spider mite damage to leaves.

Spider mites, unlike their larger arachnid cousins, don’t have fangs for biting into their prey. Instead, they have piercing mouthparts that penetrate the leaves and suck out the sap. A few spider mites have minimal impact on a plant, but larger populations can start to show visible damage to the leaves and kill the entire plant without proper control.

The first sign of spider mite damage appears as small, lightly colored dots along the leaves. After a while, vibrant leaves may fade in color and appear to have a bronze sheen. As the spider mite population grows and continues to feed on the plant, the leaves will turn yellow or red and fall to the ground. By this time, you can easily identify a spider mite infestation as the webbing covers much of the leaves and the stems.

You’ll probably notice leaf and stem damage long before you ever see any spider mites, so inspect your plants regularly to prevent a few spider mites from evolving into a devastating population. To identify a possible spider mite infestation, you should:

  • Quarantine any plant that may have spider mites.
  • Examine the underside of the leaves for webbing.
  • Inspect the entire plant with a magnifying glass.
  • Check the leaves for small dots and yellow markings.

Spider mites target everything from ornamental potted plants to agricultural crops. Vegetable crops and fruit trees suffer massive leaf loss, which causes sunburning and reduces yield for the harvest. On ornamentals, spider mites ruin the plants’ aesthetic appeal and can also kill the plants if the infestation grows out of control.

Controlling and Managing Spider Mite Infestations

A predatory mite (Anderline aa) preying on a plant-damaging mite.

Thankfully, spider mites have many natural enemies that help reduce infestations and limit population overgrowth. Some of these natural predators include:

  • Phytoline P (Phytoseiulus Persimilis)
  • Amblyline cu CRS (Predatory Mite)
  • Anderline aa (Predatory Mite)
  • Exhibitline sf ( Predatory Thrips)

In many cases, the predators take care of entire infestations without the need for human intervention. Due to chemical spraying and the loss of beneficial insects, spider mites may have less predators to worry about in the area. However, the mites may also run rampant in greenhouses and interiorscapes where workers prefer not to use chemical pesticides. These areas have less natural predators, providing a safer breeding ground for mites to grow in numbers.

Even with chemical treatment, not all pesticides work to kill spider mites. However, some pesticides have special formulas that not only eradicate spider mites but do so without harming the plant in any way. Whether you choose biological control or chemical miticides depends on the treatment area and the severity of the problem.

Monitoring the Target Area

You should always check for mites before you apply any treatment to an area. Sometimes, you may notice leaf damage after the mites have already left the plant, so treating the plant may only cause more damage depending on which treatment method you use. Because spider mites are difficult to detect, use a handheld magnifying glass to observe the leaves more closely. You can also hold a sheet of white notebook paper under the leaves as you shake the plant. The mites should fall off the leaves and onto the paper where you can see them more clearly.

After you’ve detected a spider mite infestation, the next step involves choosing a treatment option for eliminating the threat. You have three primary treatment options to choose from: biological control, chemical control and cultural control. Each method has its own advantages and disadvantages, and you may have to combine different methods to get a more effective result.

Choosing Biological Control for Eliminating Spider Mites

When spider mites have taken over gardens, crops and ornamentals, introducing natural predators into the area can have a profound effect. Natural enemies such as Galendromus occidentalis, a predatory mite, hunts and feeds on web-spinning mites. These predatory mites are about the same size as spider mites but have longer legs and teardrop-shaped bodies. They run very quickly and continue to feed on spider mites until they’ve vanished from the plant.

Predatory mites don’t feed on plants or become pests themselves. In fact, if they have no food source available in the area, they either starve and die or move elsewhere in search of prey. You can purchase predatory mites and other natural spider mite enemies as adults and release them directly on the target plants. It only takes one predator mite for every 10 spider mites to reduce population numbers. Once the predator mites have established on perennials, they may reproduce and provide residual control.

Using Chemical Control to Combat Spider Mite Infestations

Floramite SC, Avid 0.15EC and Forbid 4F for killing spider mites.

Applying chemical insecticides in the target area comes with risks. After all, if insecticides kill beneficial mite predators, you’re essentially making things worse. Carbaryl, a common chemical in pesticides, appears to affect spider mites in a positive way. In field studies, the carbaryl actually helped the spider mites to reproduce faster than mites that were left untreated. In addition, applying the insecticide during hot weather caused severe mite outbreaks within days.

Because mites don’t belong in the same category as insects, they require a different form of treatment. Miticides, such as Avid 0.15 and Floramite SC, target invasive mites while minimizing the impact on surrounding insects. These miticides work to control spider mites of all types, from the two-spotted spider mite to the clover mite. Miticides like Floramite SC help to eliminate spider mites in:

  • Greenhouses
  • Plant nurseries
  • Conifer plantations
  • Interiorscapes
  • Landscapes
  • Public, commercial and industrial areas
  • Golf courses, parks and other recreational sites

Relying on Cultural Control for Spider Mites

Dry, dusty conditions can lead to spider mite infestations in agricultural crops and throughout landscapes. To help minimize an outbreak, apply water to dusty areas and pathways regularly. Spraying trees and plants with water slows the mites’ progress and the damage they cause. You should also provide sufficient irrigation to wash away the mites as they build up on the plants.

Forcefully spraying water on plants in home gardens also helps to reduce spider mite numbers especially if you provide thorough coverage on and beneath the leaves. For added control, combine the water with insecticidal soap or oil to eradicate even more mites on the plants. However, test the soaps and oils on one or more plants first to see how they react to the treatment.

Preventing Spider Mite Infestations on Foliage

Performing preventative maintenance in the garden and on trees and shrubs can help eliminate spider mite infestations before they occur. Water the target area at adequate intervals, and use natural soaps and oils to limit populations without harming other insects. Avoid broad-spectrum pesticides that kill beneficial predators, and introduce natural predators like ladybugs to the area when you can. Being mindful of spider mites and taking preventative measures beforehand can help you avoid a serious mite outbreak and keep your plants safe, healthy and vibrant.

In writing this piece the knowledge and insight was gained through learning journey. The thoughts expressed here was learned through extensive reading and research. I was truly amazed at the amount of information that is available. A person could spend hours looking and learning on www.uvm.edu/%7Eentlab/Greenhouse%20IPM/UVMGreenhouseIPM.html The information compiled by Ms. Frank Sullivan and Skinner is both interesting and informative. You do not have to have a dictionary next to you to understand the information that is being presented and it does not put you to sleep. The UC IPM site by UC Davis www.ipm.ucdavis.edu/index.html is also a treasure trove of information and guidance. This is another public website that I am happy to say is tax payer money well spent along with the Cornell Garden-Based Learning resources available at http://gardening.cce.cornell.edu I look forward to hearing your thoughts on this subject.

How to Prevent Spider Mites In Cannabis Plants

Cannabis, just like any other plant, is susceptible to garden pests which, despite their size, can have devastating effects on a plant’s ability to grow and develop.

In this article we look at spider mites, arguably one of the most common pests affecting cannabis plants. We’ll show you exactly what they are, how to get rid of them and how to prevent them coming back.

For more articles like this and the latest cannabis-related news, grow tips and more, bookmark our site and check in with us regularly. Also, make sure to check out our earlier post for more tips on cannabis pest prevention.

WHAT ARE SPIDER MITES?

Spider mites are a common garden pest that generally lives on the undersides of plant leaves, where they may spin protective silk webs to protect themselves against the elements and other predators.

They are less than 1 millimetre (0.04 inches) in size and can be red or black in colour. Spider mites prefer hot, dry conditions and lay transparent eggs which can hatch in as little as 3 days.

Hatchlings are sexually mature in 5 days, and female mites can live for up to 2-4 weeks, laying up to 20 eggs per day.

TELLTALE SIGNS OF SPIDER MITES IN CANNABIS PLANTS

Spider mites feed off cannabis plants and cause damage by puncturing plant cells in order to feed. Spider mites affect both indoor and outdoor plants and can wreak havoc when not controlled quickly.

Spider Mites pest cannabis detection

Some initial signs of a spider mite infection include tiny spots or stippling on leaves (caused by feeding) and thin, silky webs surrounding the underside of plant leaves and branches.

Larger colonies can cause leaves to turn yellow, become limp and eventually, die off altogether. A large spider mite infection can have a significant effect on a cannabis plant; by destroying the plant’s leaves, they may stunt its ability to grow and develop, eventually resulting in lower yields.

Spider mites may also infect the surrounding areas of buds, which can affect their ability to develop and mature properly. Finally, a large enough colony can kill entire plants, although that is very uncommon.

HOW TO CONTROL AND PREVENT SPIDER MITES

Spider Mites lyfecycle

We do not recommend using chemical pesticides on spider mites. In most cases, this will only make matters worse by killing off other insects that prey on the mites.

Also, spider mites are notoriously good at developing resistance to common pesticides, so we suggest using some of the organic methods outlined below.

We also recommend addressing any environmental factors first, then following up by pruning and hosing down your plants.

ENVIRONMENTAL FACTORS

Remember, spider mites like hot and dry conditions. So, before you get started on any kind of countermeasure against a colony, try bringing down the temperature in your grow room (if possible, bring them down past 20ºC or 68ºF but be careful not to damage your plants).

Next, create some extra air circulation in your grow area. Spider mites hate windy conditions.

PRUNING AND HOSING

Once you’ve addressed any environmental factors in your grow area, it’s time to start pruning.

If you’re only dealing with a small infestation, cut down any infected areas well past the mites’ webbing and discard them in the trash. If you’re dealing with larger infections on individual plants, consider destroying them to avoid the mites spreading.

Once you’ve pruned your plants, consider hosing them down gently. This will help remove any remaining mites and will also help prevent another infestation. You may want to hose them down periodically if you find you’re dealing with mites on a regular basis.

Once you’ve done all of that, you may want to use one of the below control methods to minimise the risk of a future infestation. Remember to check up on your plants daily and to repeat treatment at least twice to avoid having the mites coming back.

Note: some growers hose down plants with a mix of water and alcohol (9:1 ratio). This mixture is known to kill mites on contact without damaging plants.

ADDITIONAL WAYS TO CONTROL SPIDER MITES

INTRODUCE OTHER INSECTS

Ladybugs, lacewings and predatory mites prey on spider mites and are generally available commercially. For the best results, introduce these insects when mite populations are low.

Ladybugs are by far the most common insect used to counter a spider mite infestation. For more detailed tips on how to use ladybugs in your garden,

Other insects that prey on spider mites include:

  • Sixspotted thrips
  • Minute pirate bugs
  • Bigeyed bugs
  • Western flower thrips
ORGANIC INSECTICIDES AND INSECTICIDAL SOAPS

There are a number of organic insecticides on the market that can help control a spider mite infestation. Here are some popular solutions we recommend trying:

  • Essentria IC3: Containing a mix of horticultural oils, this organic spray can be directly applied to your plants using a mister. However, the spray only remains active for 8-12 hours, so you may need to use it daily or combine it with another product or control method.
  • Spinosad: These products are completely organic and do not damage plants. You can apply any of these products to your plants during an infestation to kill mites on contact or add them to your plants’ water supply for long-term protection against mites and other pests.
  • NukeEm: This is a relatively new insecticide made from food-grade ingredients. It can kill mites the egg, larvae or adult stage, and doesn’t leave any residue on the plant.
  • SM-90: An organic wetting agent with a beautiful aroma. Mix this with water and apply it to your plants with a mister to kill any mites on contact.
  • Insecticidal soaps: Insecticidal soaps are great for spot-treating infested areas of your plants. They leave very little residue on your plants but you should still avoid getting any directly on your buds. Multiple treatments may be necessary as soaps do not stay active for long.
ESSENTIAL AND HORTICULTURAL OILS

There are a variety of essential oils that can help to kill and control spider mites by attacking their central nervous system.

Neem oil (extracted from the nuts of the neem tree) is considered a miticide and is the most common type of essential oil used to control mites. However, there are plenty others out there, including:

  • Eucalyptus oil
  • Cinnamon oil
  • Lemon oil
  • Peppermint oil
  • Rosemary oil
  • Eucalyptus oil
  • Cinnamon oil
  • Lemon oil
  • Peppermint oil
  • Rosemary oil
  • Eucalyptus oil
  • Cinnamon oil
  • Lemon oil
  • Peppermint oil
  • Rosemary oil
  • Eucalyptus oil
  • Cinnamon oil
  • Lemon oil
  • Peppermint oil
  • Rosemary oil

These oils can be mixed with water and liberally applied to your plants. However, many of these oils are very aromatic, so you may want to avoid getting them on your buds to avoid changing their taste or smell.

Alternatively, you may want to treat your plants periodically with horticultural oils. We generally recommend using vegetable oils, such as canola, soybean or cottonseed.

What are Spider Mites?

If your plants have stopped thriving, you may think that low water levels or poor soil balances may be the cause. However, certain bugs may be to blame. Aphids and weevils are notorious agricultural pests. However, spider mites are also commonly encountered around homes and gardens.

Spider mites are arachnids, meaning they are related to spiders, ticks and scorpions, rather than insects. Spider mites belong to the family Tetranychidae. Some of these species spin silk and form webs, mostly to protect their eggs and young from predators.

Spider mites grow from egg to adult over the course of five stages. Some female spider mites have an average lifespan of 30 days and can produce 100 eggs on average during that time. In the case of the twospotted spider mite, the young can complete their development in as few as five days, meaning that a new generation is now ready to reproduce. For this reason, twospotted spider mite populations tend to explode, especially under favorable climatic conditions (hot and dry). Sizable populations of twospotted spider mites are also more likely to coat plant leaves and stems with webbing.

There are many different species of spider mites, and, while they do come in a variety of colors, it is often difficult to identify them with the naked eye. Spider mites are virtually microscopic — adults average 1/50 of an inch in length, which is about as large as the size of the period at the end of this sentence.

If you notice stippling or webbing on your plants, use a magnifying glass to check both sides of its leaves. If you are still unsure if you have a spider mite problem, take a sheet of white paper and turn a leaf over on top of it. Tap it gently. Wait and watch for movement — if spider mites have infested the plant, you should be able to see them moving across the surface of the blank paper.

What Damage Can Spider Mites Cause?

Spider mites feed on the chlorophyll in plants. They use their piercing mouthparts to puncture individual plant cell walls and suck out the vital fluids those cells contain. Leaves bearing many tiny white spots or showing a stippled appearance are a likely sign of a spider mite infestation. If spider mites are allowed to continue feeding unabated, these damaged leaves will likely turn brown and eventually drop off the plant. Plants that are over-fertilized may be more attractive for female twospotted spider mites as they contain more proteins and amino acids which are a food source for this pest.

Twospotted spider mites may also feed on grass, soybeans, corn and fruit trees, among other crops and plants.

There are other plant feeders that can cause damage similar to spider mites. That’s one reason why it’s important to contact a trained professional if you spot what looks like spider mite damage.

How to Help Prevent Spider Mites

Preventative maintenance is the best strategy. Check your landscape plants every one to two weeks for signs of spider mites. Because indoor temperatures are stable and climates tend to be drier indoors, house plants should be checked weekly. Spider mites are particularly fond of fruit trees, vegetables and popular ornamentals, such as roses.

When watering your plants, also clean them. Use a high-pressure hose and spray plant leaves weekly. Be sure to adjust the water pressure so that it will still be safe for your plants, though. Also be sure to spray the underside of the leaves, as spider mites are most likely to congregate there.

Finally, if you are purchasing new plants, be sure to inspect them for signs of spider mite damage. Spider mites that you unsuspectingly import to your garden or home can rapidly colonize either — or both.

Need help with what to do in your garden?

Q What are spider mites?

A Spider mites are tiny wingless insect-like creatures that have eight legs and a one-piece body. They are so small that a hand lens is needed to see them clearly. Greenhouse spider mites (Tetranychus urticae) are also known as two-spotted spider mite or red spider mite. Another spider mite found indoors is the carmine spider mite (Tetranychus cinnabarinus). Both species feed on plant sap.

Caption: Affected leaves often have a speckled appearance

Q Can you tell me more about spider mites?

A Tiny (0.14mm diameter) eggs hatch into white, six-legged larvae. The eggs are easily seen with a hand lens, but the larvae are harder to spot. The adult female lays 4-6 eggs a day, starting when they are 36 hours old. It is at this adult stage that they take on their characteristic two-spotted appearance. The whole life cycle can take as little as three days in hot conditions, though in cooler weather it may extend to a month.

By September, the shorter days and slower plant growth stop their reproduction. The remaining females turn red and find sites to hibernate, such as in the soil, on bark and on greenhouse walls, even on pots. The first adults seen in spring are also bright red.

Q Are spider mites something to worry about?

A Although they are extremely small, spider mites can build up to enormous numbers in the right conditions, making them one of the most destructive pests in the garden. They can ruin foliage, spoiling ornamental plants and reducing yields of vegetables, fruit and salad crops. Heavy attacks can even kill plants.

Q How can I tell if spider mites are present?

A Look underneath the leaves for tiny slow-moving mites with two dark spots on their backs. A hand lens will help. Another test is to hold a sheet of white paper beneath the plant and shake the foliage. The mites will fall on to the paper and can be clearly seen. Look out for a fine webbing on the underside of the leaves and on young shoot tips in advanced cases. Check for yellowing (chlorosis) and minute speckling of leaves. In the later stages, brown falling leaves and needles are also seen. Cucumbers and melons, in particular, can be severely affected by a spider-mite attack.

Some strains of spider mites can cause the plant hypertoxic shock: the leaves become bleached, wilted and dried-up.

Q Which plants are most at risk from spider mites?

A Spider mites have been found on more than 180 different species of plant. However, some are more susceptible than others. Ones likely to be affected include: begonia, brugmansia, carnation, chrysanthemum, crocosmia, cucumber, dahlia, datura, French and runner beans, fuchsias, fruit trees and bushes, houseplants, impatiens, melon, pelargoniums, primulas, spruce (Picea), strawberries and vines.

Q What causes spider-mite outbreaks?

A Hot, dry, dusty conditions lead to spider-mite problems. They are often worst in greenhouses, conservatories and on houseplants. These conditions encourage the mites to feed often, causing damage to the plants every time they feed. Even plants that do not normally suffer from spider mites become at risk in these conditions. Unhealthy plants are especially vulnerable. Cool, moist conditions can help to reduce spider-mite populations, perhaps by limiting their breeding success.

Q Can spider-mite attacks be avoided?

A Spider mites are less likely to attack if you give the plants the best possible conditions, misting foliage regularly. However, take care not to overdo it, as it can encourage fungal disease.

Get rid of the worst-affected plants as spider mites spread to other plants from them.

Keep new plants separate from others for the first two weeks, in case they are infested.

When you bring plants back indoors after a summer outside, check them carefully for spider mites – it’s best to throw out infested plants.

Q Are there any pesticides available for the control of spider mites?

A There are a range of insecticides for control of spider mites. However, bear in mind that if you have used a pesticide and then want to use a biological control, you’ll need to wait at least a month, as residues from spraying may kill the predators you introduce. By this time the mites will probably be out of control.

Q Is there a spray for spider mites that’s suitable for organic gardeners?

A Yes, we recommend ready-to-use pyrethrum-based sprays which are suitable for traditional or organic gardeners. Spray the leaf undersides every seven days. Biological control can be used safely three to four days after spraying.

Q Can you tell me more about biological control for spider mites?

A Introduced predatory mites Phytoseiulus persimilis can eliminate spider mites indoors. They can eat up to five adults or 60 eggs per day. The drawback is that they should be introduced when there are only a few spider mites present. You have to examine your plants closely from April onwards, using a hand lens to spot the first few mites. When you see them, order predators from the suppliers listed here. You might have to make further introductions throughout the summer, but often one will be enough.

The effectiveness of the biologicial control is reduced if the conditions are too hot. If you use shading paint on glass and ventilate the greenhouse well, they should be all right.

You can keep an eye on the phytoseiulus by looking with a hand lens for bigger, rounder, redder mites than spider mites. Phytoseiulus won’t survive the winter, so you have to introduce it every year.

If spider mite is a problem every year, then try Amblyseius andersoni. It works more slowly than phytoseiulus, but it can be introduced before overwintering spider mites re-emerge in mid-late March. This is because it can survive for a few weeks without food and also eats pollen, thrips, springtails and other invertebrates. It’s active at temperatures as low as 6°C and is also more tolerant of hot, dry conditions. It can be used outside as well as under protection, provided temperatures are suitable. While it can overwinter in the greenhouse, this probably won’t be in sufficient numbers to keep spider mite in check.

Release all predators (according to the instructions) on to the problem plants.

Caption: Use biological control to treat spider mites indoors

Suppliers of spider-mite controls

Defenders 01233 813121 defenders.co.uk

Green Gardener 01493 750061 greengardener.co.uk

Ladybird Plant Care 01825 724621 ladybirdplantcare.co.uk

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