Spider webs on trees

We’ve all heard horror stories about how pests and diseases have wreaked havoc on trees, completely devastating properties.

Luckily, most instances aren’t that extreme and can be fixed if you know the warning signs and take quick action. So, it’s important you have someone maintaining your landscape who knows when trees are in distress and what’s causing the issues — whether it’s the result of insects or the Texas drought season.

What And Where Are Spider Mites?

A common pest we see a lot of around the state is the spider mite. They are attracted to hot, dry conditions, and Texas definitely has plenty of that. Spider mites are mostly found on the underside of leaves and leave behind silk webs, eggs and damage.

Some trees that are susceptible to this insect include cypress and cedar trees. Here are a few varieties that are especially known for having spider mites:

  • Italian cypress
  • Leyland cypress
  • Bald cypress
  • Hinoki cypress

Early signs of spider mite damage include spots on foliage or leaves that curl up and fall off. While they are more of an aesthetic concern, spider mites can kill some plants if there is a really large population of them. If you see signs of this pest, you’ll want to take steps to end their destructive path.

So how can you get rid of spider mites on cypress and cedar trees?

Take A Natural Approach To Spider Mites

The normal course of action to deal with insects is spraying a chemical pesticide on the infected area. But that might not be the best solution if your trees have spider mites.

Pesticides will kill beneficial insects that prey on spider mites, and the mites can also develop a resistance to the chemicals. So instead of taking that approach, here are some other options for getting rid of spider mites.

  • Prune branches that have spider mites on them. Make sure to cut past any webbing or plant damage you see, and put the branch into a trash bag after pruning to keep from spreading the mites to other plants.
  • Spray plants to wash off the mites.
  • Keep the trees well irrigated since plant stress and dry conditions can attract spider mites and other insects.
  • Spot treat the trees with insecticidal soap.
  • In extreme situations, you could apply a less-toxic pesticide.

The best course of action for your spider mite infestation depends on the extent of damage on your trees. So, it’s important to find a commercial landscape company who understands how to spot insects and knows the best solution to keep your plants healthy.

Bring In A Pest And Tree Expert

Your maintenance company should be your eyes on the property and catch any potential issues before they become major ones. That should include proactive services like checking plants for pests, watching for signs of stress in turf and plants and ensuring the irrigation system is working correctly.

Landscape maintenance shouldn’t just be about giving your property curb appeal, so hire a company that provides a full scope of services.

Native offers environmentally friendly commercial landscape enhancements, maintenance, design, construction and irrigation services for commercial properties in Austin, Houston and McAllen, Texas.

Our experienced team knows how to inspect and treat trees that have pest problems, and we will keep you updated on their progress throughout.

You have enough on your plate already, so don’t add dealing with insects and plant damage to your list.

Call Native at 512-918-2270, or fill out a form online to schedule a free onsite consultation and see how we can enhance your landscape.

How To: Get Rid of Spider Mites

Photo: istockphoto.com

Tiny, sap-sucking arachnids known as spider mites can be a problem any time of year, out in your garden and plaguing houseplants and greenhouse varieties, too. With females able to lay as many as 300 eggs every few weeks, spider mite populations can explode in a matter of days. Tell tale signs that you’ve been infested include speckled leaves or brownish webbing on the surface of leaves. Unfortunately, employing chemicals to control them can be a two-pronged problem: First, mites can develop resistance, and second, pesticides often kill such beneficial insects as ladybugs that like to feast on mites. Instead, go with the simple techniques and non-toxic remedies outlined here for in this guide on how to get rid of spider mites.

MATERIALS AND TOOLS Available on Amazon
– Magnifying glass
– White paper
– Hose with spraying attachment
– Spray bottle (optional)
– Sponge
– Bucket
– Pruning shears
– Plastic bags
– Rosemary oil
– Lemonscented liquid dish detergent
– Onequart jug

Photo: istockphoto.com

STEP 1
Your plants are in trouble: Leaves may be blotchy, be-webbed, streaked with silver or gold, or turning brown and falling off. But are spider mites to blame? These pests are less than a millimeter long, so grab a magnifying glass and inspect the underside of leaves, where they congregate. If you can’t see the culprits, place a piece of white paper under foliage and shake the leaves, then examine what falls on the sheet. Slow-moving, eight-legged pests—red, yellow, brown, or green in color—mean you’ve got spider mites. Two-spotted spider mites, so called for the duo of dots on their backs, are deemed “particularly troublesome” by experts, but diligent treatment can curb their invasion.

STEP 2
Simply wash the buggers away! Pressure-sprayed water is a surprisingly effective against spider mites, whether using a power spray from your hose outside or just a strong stream from a spray bottle on houseplants. Blast plants from below to hit the back of leaves. Then, take a clean, water-dampened sponge to wipe the backs of leaves, rinsing the sponge after each wipe by dipping it in a bucket of water.

STEP 3
Prune any leaves and stems spider mites have attacked, placing the clippings in a plastic bag and putting it in the trash, not your compost (eggs can lay dormant until the perfect hatching climate arises). If the entire plant has evidence of mites, or its health seems too far-gone to bounce back, consider pulling it completely to prevent infestation from spreading to neighbors.

STEP 4
Mix this all-natural, non-toxic solution that’ll banish the invaders without harming phytoseiulus persimilis, a beneficial mite that snacks on spider mites.
• ½ ounce rosemary essential oil (found in natural health stores)
• 1 quart tap water
• 1 teaspoon of lemon-scented liquid dish soap

A soap-and-water combo is often used as a repellent on its own, but rosemary oil helps emulsify the solution, making it easier to spray. Combine all ingredients in a jug, shake well, and fill a spray bottle. Shake thoroughly before use, spraying plants either early or late in the day, avoiding the hottest periods. Spray plants (and surrounding soil) daily for at least four days, then on alternate days for two weeks. Once you’ve got the situation thoroughly under control, continue spraying once a week to keep plants healthy.

STEP 5
For outdoor plants, consider introducing predatory mites, ladybugs, lacewings, and other beneficial insects (find them online or at nurseries) once you’ve gotten the problem in hand. They’ll eat the spider mite larvae, mite adults, and all mites in between that try to muscle in on your restored territory. You may also want to put in companion planting, interspersing Chinese parsley, chives, dill, chrysanthemums, garlic, and onion throughout your garden to repel spider mites.

STEP 6
When plants are stressed, they’re more prone to invasion by spider mites and other opportunistic feeders. So keep them watered per their needs and ensure excess water drains well. Use nutrient-rich soil and vary feeding accordingly as seasons change. Be sure plants have the right light conditions for their species. Then be vigilant, inspecting for early signs of infestation and doing what it takes to nip it in the bud.

The Oasis Lawn & Tree Care Blog

From Rocky to The Karate Kid—to almost any other classic sports movie ever made—if we’ve learned anything, it’s that the little guy can win. However, in the case of the tiny-but-powerful spider mite, this is one time we’d like to see the underdog lose.

Unfortunately, that’s often not the case. If you suspect you might have mites on your trees and shrubs—possibly because you’re seeing telltale symptoms or you’ve even scouted them out—then you could be worrying that you’ll lose your plants.

You’re right to be concerned. Mites may be small, but they’re highly destructive. While spider mites are the most “notorious” mite, and the one that we’ll focus on in this article, you should know there are other types of mites found in landscapes as well.

If you’re worried about how to get rid of spider mites, then we’ve got you covered. Understanding more about these mighty little menaces will help you win the battle against them.

The Mighty Spider Mite

Spider mites are not insects but are more closely related to spiders, hence their name. These arachnids (in adult form) have eight legs, an oval body, and no antennae. Spider mites belong to the family “Tetranychidae,” which includes about 1,200 species.

Though small (adults average only 1/50th of an inch), the spider mite’s power lies in its numbers. Spider mites on trees can rapidly multiply. That’s because some female spider mites have an average lifespan of 30 days and can produce 100 eggs on average in their lifetime. Since some young spider mites can complete their development in as little as five days, new generations are quickly reproducing. This means that, if not addressed, you can develop a total infestation.

Plants Commonly Infected by Spider Mites

There are quite a few plants in Cincinnati, Dayton, OH, and Northern Kentucky that can be infected by spider mites. Some of the plants that are commonly infected by spider mites include, but are not limited to, the following:

  • Burning Bush
  • Spruce
  • Boxwood
  • Arborvitae
  • Juniper
  • Hemlock
  • Pine
  • Douglas-Fir
  • Hemlock

Unfortunately, this only names some of the plants that spider mites can attack. To give you some idea, the spruce mite, despite its selective name, actually feeds on more than 40 different species of conifers—and that’s just one type of spider mite. There are many different species of spider mites found in Northern Kentucky and Ohio.

Spider Mites on Trees: Symptoms to Know

Spider mites use their piercing mouthparts to feed on the chlorophyll in plants, which can lead to tiny white spots or a stippled appearance. Both of these symptoms are indicators that you’re dealing with a spider mite infestation. As these pests continue to feed, the damaged foliage will eventually turn brown and start to drop off the plant. Many spider mites also produce minuscule webbing, which is another telltale sign that you’re dealing with this pest.

If you suspect that you have a spider mite infestation, you can attempt to examine the leaves of your plant using a magnifying glass—but even then, they can be challenging to see.

You might also try to hold a sheet of white paper beneath a branch and give it a shake. On a piece of crisp white paper, you may be able to see them scurrying. You could also drag your hand across the paper as squishing them will leave tiny streaks.

How to Get rid of Mites on Trees and Shrubs

Protecting your plants from these harmful pests means implementing spider mite control. When it comes to success, the approach really matters. For instance, it’s important to rotate your miticides with different modes of action so that the mites do not become resistant to the product being used.

In addition, it’s also important to note that there are both harmful and beneficial mites on your trees and shrubs. The beneficial mites actually eat the harmful ones. However, if a general miticide product is used, it’s going to kill all of them. It’s critical to use a selective product that won’t kill the predatory mites.

At Oasis Turf & Tree, we use separate tanks for our insecticides and our miticides, an extra step that a lot of companies don’t take. A lot of tree care companies will just mix tanks and spray everything. However, there may be other beneficial insects in the landscape that feed upon spider mites. By killing those off, you give spider mites the upper hand.

Another differentiator is that we’ll also make the hard recommendations when they’re necessary. Sometimes the best thing you can do for your landscape is to remove the plant.

A lot of tree services in Cincinnati, Dayton, OH, or Northern Kentucky will not want to tell you that and will just keep on spraying and getting paid for their work. However, we’re actually scouting and determining the best course of action for each plant—even if it’s removal. If your plant is too far gone, we’re not going to just keep spraying it and making money off of something which no one can restore.

Protecting the Beloved Plants in your Landscape

Unfortunately, by the time that you notice damage from a spider mite problem, chances are you already have a severe infestation that has been going on for a long period of time. While you may not have realized that your plants were slowly becoming dull, it’s probably been happening, right under your nose, for quite a while. It may take a long period of time to save your plant and restore it to its intended beauty.

That’s why the best thing you can do for your trees and shrubs is to protect them with preventative care. Being part of a tree and shrub care program can help ensure that your trees will better withstand pest problems as well as disease and environmental stressors. Choosing a tree spraying service that will take a customized approach to your landscape will be key in protecting it.

Don’t let the might of the powerful spider mite bring you down—or the power of any other pest or disease, for that matter. By choosing a company that can address your problem and also provide protection going forward, you can take back your landscape and claim victory over these destructive pests.

If you want to learn more about tree and shrub health care for your Cincinnati, Dayton, OH, or Northern Kentucky home, call us today at 513-697-9090 to get your quote, let us help you choose a stand-alone program or bundle it with other services, and then sit back and relax knowing you’re in good hands.

Image Sources: spruce spider mite, predatory mite, two-spotted spider mite, mite damage and webs, Picea glauca

How to Manage Pests

Pests in Gardens and Landscapes

Spider Mites

Revised 12/11

In this Guideline:

  • Identification
  • Life cycle
  • Damage
  • Management
  • About Pest Notes
  • Publication
  • Glossary

Figure 1. Spider mites.
Figure 2. Mite colony on underside of leaf.
Figure 3. Webspinning mites can produce copious amounts of webbing.
Figure 4. Twospotted spider mite eggs.
Figure 5. Spider mite life cycle, development of a typical plant-feeding spider mite—egg, larva, two nymphal stages, and adult.
Figure 6. Feeding by webspinning mites first appears as leaf stippling.
Figure 7. The western predatory mite, shown here attacking a twospotted spider mite, is an important predator.

Figure 8. The sixspotted thrips feeds on spider mites and their eggs.
Figure 9. Larvae of predatory midges, such as this Feltiella species, prey on spider mites.

Mites are common pests in landscapes and gardens that feed on many fruit trees, vines, berries, vegetables, and ornamental plants. Although related to insects, mites aren’t insects but members of the arachnid class along with spiders and ticks. Spider mites (Figure 1), also called webspinning mites, are the most common mite pests and among the most ubiquitous of all pests in the garden and on the farm.

Webspinning spider mites include the Pacific spider mite, twospotted spider mite, strawberry spider mite, and several other species. Most common ones are closely related species in the Tetranychus genus and can’t be reliably distinguished in the field. However, there is little need to do so, since their damage, biology, and management are virtually the same.

IDENTIFICATION

To the naked eye, spider mites look like tiny, moving dots; however, you can see them easily with a 10X hand lens. Adult females, the largest forms, are less than 1/20 inch long. Spider mites live in colonies, mostly on the undersurfaces of leaves; a single colony may contain hundreds of individuals (Figure 2). The names “spider mite” and “webspinning mite” come from the silk webbing most species produce on infested leaves (Figure 3). The presence of webbing is an easy way to distinguish them from all other types of mites and small insects such as aphids and thrips, which can also infest leaf undersides.

Adult mites have eight legs and an oval body with two red eyespots near the head end. Females usually have a large, dark blotch on each side of the body and numerous bristles covering the legs and body. Immatures resemble adults (except they are much smaller), and the newly hatched larvae have only six legs. The other immature stages have eight legs. Eggs are spherical and translucent, like tiny droplets, becoming cream colored before hatching (Figure 4).

LIFE CYCLE

In some parts of California, spider mites may feed and reproduce all year on plants that retain their green leaves throughout the winter. In colder areas and on deciduous trees that drop their leaves, webspinning mites overwinter as red or orange mated females under rough bark scales and in ground litter and trash. They begin feeding and laying eggs when warm weather returns in spring.

Spider mites reproduce rapidly in hot weather and commonly become numerous in June through September. If the temperature and food supplies are favorable, a generation can be completed in less than a week (Figure 5). Spider mites prefer hot, dusty conditions and usually are first found on trees or plants adjacent to dusty roadways or at margins of gardens. Plants under water stress also are highly susceptible. As foliage quality declines on heavily infested plants, female mites catch wind currents and disperse to other plants. High mite populations may undergo a rapid decline in late summer when predators overtake them, host plant conditions become unfavorable, and the weather turns cooler as well as following rain.

DAMAGE

Mites cause damage by sucking cell contents from leaves. A small number of mites usually isn’t reason for concern, but very high populations—levels high enough to show visible damage to leaves—can damage plants, especially herbaceous ones. At first, the damage shows up as a stippling of light dots on the leaves; sometimes the leaves take on a bronze color. As feeding continues, the leaves turn yellowish or reddish and drop off. Often, large amounts of webbing cover leaves, twigs, and fruit. Damage is usually worse when compounded by water stress.

Loss of leaves won’t cause yield losses in fruit trees during the year of infestation unless it occurs in spring or very early summer, but it may impact next year’s crop. On annual vegetable crops—such as squash, melons, and watermelons—loss of leaves can have a significant impact on yield and lead to sunburning. On crops such as sugar peas and beans, where pods are attacked, spider mites can cause direct damage. On ornamentals, mites are primarily an aesthetic concern, but they can kill plants if populations become very high on annual plants. Spider mites are also important pests of field-grown roses.

MANAGEMENT

Spider mites have many natural enemies that often limit populations. Adequate irrigation is important, because water-stressed plants are most likely to be damaged. Broad-spectrum insecticide treatments for other pests frequently cause mite outbreaks, so avoid these pesticides when possible. Sprays of water, insecticidal oils, or soaps can be used for management. Always monitor mite levels before treatment.

Mites are tiny and difficult to detect. You’ll usually notice plant damage such as stippled or yellow leaves before you spot the mites themselves (Figure 6). Check the undersides of leaves for mites, their eggs, and webbing; you’ll need a hand lens to identify them. To observe mites more closely, shake a few off the leaf surface onto a white sheet of paper. Once disturbed, they will move around rapidly. Be sure mites are present before you treat. Sometimes the mites will be gone by the time you notice the damage; plants will often recover after mites have left.

Spider mites have many natural enemies, which limit their numbers in many landscapes and gardens, especially when undisturbed by pesticide sprays. Some of the most important are the predatory mites, including the western predatory mite (Figure 7), Galendromus (formerly Metaseiulus) occidentalis, and Phytoseiulus mite species. Predatory mites are about the same size as plant-feeding mites but have longer legs and are more active; they also are more teardrop-shaped than spider mites.

Various other insects are also important predators—sixspotted thrips (Scolothrips sexmaculatus) (Figure 8), the larvae and adults of the spider mite destroyer lady beetle (Stethorus picipes), the larvae of certain flies including the cecidomyid Feltiella acarivora (Figure 9), and various general predators such as minute pirate bugs, bigeyed bugs, and lace­wing larvae. Western flower thrips, Frankliniella occidentalis, can be an important predator on spider mite eggs and larvae, but this species will also inflict severe damage to plants if mites aren’t present on which to feed.

The purchase and release of predatory mites can be useful in establishing populations in large plantings or orchards, but the best results are obtained by creating favorable conditions for naturally occurring predators, such as avoiding dusty conditions and insecticide sprays. The major predator mites commercially available for release are the western predatory mite and Phytoseiulus. The western predatory mite is more effective under hot, dry conditions. These predators don’t feed on foliage or become pests; thus if pest mites aren’t available when predatory mites are released, the predators starve or migrate elsewhere.

If you wish to establish predators in a heavily infested orchard or garden that has few predators, use a soap spray or selective miticide to bring pest mites to a lower level and then release predatory mites. A good guideline is that one predator is needed for every 10 spider mites to provide control. More than one application of predatory mites may be required if you want to reduce pest populations rapidly. Concentrate releases in hot spots where spider mite numbers are highest. Once established on perennials, predatory mites may reproduce and provide biological control indefinitely without further augmentation unless nonselective insecticides are applied that kill the predators.

Cultural Control

Cultural practices can have a significant impact on spider mites. Dusty conditions often lead to mite outbreaks. Apply water to pathways and other dusty areas at regular intervals. Water-stressed trees and plants are less tolerant of spider mite damage. Be sure to provide adequate irrigation. Mid­season washing of trees and vines with water to remove dust may help prevent serious late-season mite infestations.

In gardens and on small fruit trees, regular, forceful spraying of plants with water often will reduce spider mite numbers adequately. Be sure to get good coverage, especially on the undersides of leaves. If more control is required, use an insecticidal soap or oil in your spray, but test the product on one or two plants to be sure it isn’t damaging to them. (See Chemical Control below.)

Spider mites frequently become a problem after applying insecticides. Such outbreaks are commonly a result of the insecticide killing off the mites’ natural enemies but also occur when certain insecticides stimulate mite reproduction. For example, spider mites exposed to carbaryl (Sevin) in the laboratory have been shown to reproduce faster than untreated populations. Carbaryl, some organophosphates, and some pyrethroids apparently also favor spider mites by increasing the level of nitrogen in leaves. Insecticides applied during hot weather usually appear to have the greatest effect, causing dramatic spider mite outbreaks within a few days.

If a treatment for mites is necessary, use selective materials, preferably insecticidal soap or insecticidal oil. Both petroleum-based horticultural oils and plant-based oils such as neem, canola, or cottonseed oils are acceptable. There are also a number of plant extracts formulated as acaricides (a pesticide that kills mites) that exert an effect on spider mites. These include garlic extract, clove oil, mint oils, rosemary oil, cinnamon oil and others. Don’t use soaps or oils on water-stressed plants or when temperatures exceed 90°F. These materials may injure some plants, so check labels and/or test them out on a portion of the foliage several days before applying a full treatment. Oils and soaps must contact mites to kill them, so excellent coverage, especially on the undersides of leaves, is essential, and repeat applications may be required.

Sulfur sprays can be used on some vegetables, fruit trees, and ornamentals. This product will burn cucur­bits and other plants in some cases. Don’t use sulfur unless it has been shown to be safe for that plant in your locality. Use liquid products such as sulfur and potash soap combinations (e.g., Safer Brand 3-in-1 Garden Spray) rather than sulfur dusts, which drift easily and can be breathed in. Don’t use sulfur if temperatures exceed 90°F, and don’t apply sulfur within 30 days of an oil spray. Sulfur is a skin irritant and eye and respiratory hazard, so always wear appropriate protective clothing.

WARNING ON THE USE OF PESTICIDES

PUBLICATION INFORMATION

Pest Notes: Spider Mites
UC ANR Publication 7405

Author: L. D. Godfrey, Entomology, UC Davis

Produced by UC Statewide Integrated Pest Management Program University of California, Davis, CA 95616

PDF: To display a PDF document, you may need to use a PDF reader.

Top of page

Integrated Pest Management (I.P.M.) for Spider Mites

Spider mites can be a serious problem in the landscape. They are often brought in from external sources on purchased plant material, however they can be blown in with the help of wind currents. They feed on many different herbaceous ornamental and woody plants, vegetable plants, fruit bearing plants, and even broadleaf and conifer trees. The name “spider mite” comes from the silk webbing they spin similar to spiders.

Spider mites are most effectively managed when Integrated Pest Management (I.P.M.) is practiced. In short, IPM is the use of multiple control strategies in a comprehensive and preventative approach to reduce pest populations, maintaining plant health, and minimizing the use and impact of pesticides in the environment. These management strategies involve mechanical, physical, cultural, biological, and chemical controls.

Scouting & Identification

Spider mites feed on the leaves through their piercing-sucking mouthparts. They remove contents from individual plant cells, leaving behind the cell wall, which makes the emptied cells appear silvery. The most noticeable damage of symptom of infestation is white stippling on the leaves. Heavily infested plants take on a faded, yellowish or greyish cast. Severely infested plants are covered by a thin layer of webbing created by the large numbers of spider mites.

A severe spider mite infestation has caused stippling damage on this Eleagnus pungens.
John Ruter, University of Georgia, Bugwood.org.

Webbing will be apparent on plants with high populations of heavy spider mites.
Bugwood.org Images.

When examining plants, it is best to take a white sheet of paper and tap the leaf several times with the hand, examine the paper for creatures that are dislodged. To the naked eye, all mites will look like little dots running around on the paper. Using a magnification aid can help. A simple 10X hand lens (jewelers loupe), or even a pair of high magnification reading glasses, can aid in seeing and identifying different mite species on the paper.

Twospotted spider mites are almost microscopic and require a 20X Spider Mite (Tetranychus urticae).
John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

There are hundreds of species of spider mites in South Carolina, but not all cause damage to desirable plants in landscapes and gardens. Three species are most commonly encountered and damaging to ornamental plants – the twospotted spider mite (Tetranychus urticae), the spruce spider mite (Oligonychus ununguis), and the southern red mite (Oligonychus ilicis, McGregor), The twospotted spider mite (Tetranychus urticae) are easily identifiable by two spots on their backs that look like saddle bags. Twospotted spider mites are typically the most common mite seen on many plant species in the home garden and landscape, particularly in the warmer summer months.

Another serious mite that can cause problems is the Spruce spider mite (Oligonychus ununguis). Infested plants often take on a brownish appearance. Host plants include spruce, arborvitae, juniper, hemlock, pine, and other conifers. Dwarf Alberta spruce are the preferred host, and are even known to “have free mites with every purchase”. Spruce spider mites prefer cooler temperatures and are more problematic in spring and fall. Southern red mite (Oligonychus ilicis, McGregor) is another cool temperature mite pest, seen in spring and fall, particularly on Rhododendron and Camelia species. These mites are easily seen due to their red body color and can affect many other species of plants.

Spruce spider mites (Oligonychus ununguis) on a Norway spruce (Picea abies (L.) Karst.).
Petr Kapitola, Central Institute for Supervising and Testing in Agriculture, Bugwood.org

A severe spider mite infestation has caused stippling damage on this ‘Otto Luyken’ laurel Prunus laurocerasus ‘Otto Luyken’.
Frank A. Hale, University of Tennessee, Bugwood.org

Cultural Controls

Cultural controls for spider mites mainly involve reducing plant stress and ensuring the plant’s environment is not conducive for spider mite development. Garden areas that remain dry, such as along pathways and landscape bed edges, are among the first place spider mites will be found. It is best to ensure plants are watered adequately, especially during periods of drought, as spider mites will often be worse on drought stressed plants first. In greenhouses or indoor settings, higher humidity levels can reduce spider mite populations and damage.

Mechanical Control

Similar to aphids, spider mites can be rinsed off of plant leaves. Rinsing treatments must be done frequently enough to ensure the mites will not climb back up the plants. Mid-season washing of the leaves can help reduce the potential for spider mite population booms. Unfortunately, rinsing is not effective on high populations.

Biological Control

One of the best preventative methods for managing spider mite control is using and encouraging the presence of natural enemies. Most of the predators that feed upon plant-damaging mites, are beneficial mites. They can be purchased from online sources, and are becoming more readily available. Not all predatory mites are created equal. Be sure to read all specifications, technical information, and ensure that the pest mites have been positively identified. Take a sample of infested leaves to the local Cooperative Extension Service for a positive identification. For a nominal fee the sample will be sent to the Plant and Pest Diagnostic Clinic for a positive identification.

Predatory mites that are readily available come in several product forms. The simplest is loose packed in cardboard tubes. In this package, the mites are packed on a carrier, such as saw dust, oat bran, vermiculite, or other material, that can be sprinkled over plants. These products are excellent for making both general broadcast applications over an area, or on individual plants. Another delivery method includes sachets. Sachets contain a similar material as in the tubes, but in a small packet with a tiny hole. They are designed to be placed on or near plants and then they slowly release mites over a period of time. In a long term setting such as in landscape, garden, or house plant, these sachets work very well. Replenishment times can even be set to a smart phone for reminders of when to replace the sachet.

The number one predator for twospotted spider mites is the Persimilis mite (Phytoseiulus persimilis). This mite works best at temperatures between 55 °F and 85 °F. However, above 85 °F, they cannot keep up with the twospotted spider mite populations. They are best released in the spring and fall. In the garden they can be applied at rate of 1 mite per square foot, but individual plants can also be treated.

During hot summer months, the Swirski mite (Amblyseius swirskii) works best on twospotted spider mites. Swirskii works best at temperatures above 68 °F. They are very aggressive and can be applied generally at a rate of 5 to 10 mites per square foot, or put onto individual plants. A side benefit is that they will also feed on some species of thrips, and whiteflies.

The Californicus mite (Amblyseius californicus) is another choice for twospotted spider mite. These mites work best at temperatures between 55 °F and 110 °F. They don’t do well for large pest populations, so they are best used as a preventative measure. Typical rates for broadcast applications are 1 to 5 mites per square foot, and individual plants can be treated as well.

For indoor or greenhouse settings, Mesoseiulus longipes can be used similarly to the Persimilis mite. These mites work better at low humidity, and can be used on indoor plants where other mites cannot. Release rates are 1 to 3 mites per leaf, and they attack similar prey as Persmilis mites.

Chemical Control

When all other control measures have failed to keep the populations under control, a chemical miticide may be needed. The primary goal with miticide use is to choose the one with minimal impact to pollinators and natural enemies, but still be effective on the insect causing the problem. Before using a miticide, be sure to read and follow ALL label directions. The label is the law! The product label is the final authority on what plants and in what areas the product can be applied and at what rate. When purchasing a miticide, be sure to look on the package for the active ingredient and choose the product with the proper active ingredient to control the pest.

The first effective choice to spray would be either an insecticidal soap or horticultural oil. These miticidal products are designed to coat the mite’s exoskeleton and cause it suffocate. These products also can kill beneficial mites and insects upon contact, but they do not have residual activity. So only beneficial mites, insects, and pollinators that were directly hit by the application will be harmed. Note that these products can be phytotoxic (damaging to foliage) to drought stressed plants, or when temperatures of 90 °F or higher. Applications should be made when temperatures are cooler, such as during the mid- to late evening to avoid any potential phytotoxic effects. Other miticidal oils include those derived from botanicals such as rosemary, clove, and cinnamon oil. These oils can be effective, but use the same precautions as with soaps and other oils.

There are stronger miticides available to control spider mites. However, most are listed as “professional use only”, “licensed applicators”, or labeled as “restricted use pesticides”, which means only individuals with a commercial pesticide license can handle and use them. If all other treatments, including oils have not provided adequate control, it is best to contact a licensed company, such as a lawn care or landscape management company, to make the application.

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