Predatory Mite Pest Control – Using Predatory Mites In The Garden

Predatory Mite Pest Control – Using Predatory Mites In The Garden

By: Bonnie L. Grant, Certified Urban Agriculturist

Mites are infinitesimally tiny insects that suck plant juices and sap the vitality of your garden specimens. Predatory mites in the garden are the security system you need to stop plant-eating mites. What are predatory mites? These minute bugs eat the eggs, larva, and adults of the plant-eating variety of mite. Discover how to use predatory mites and where to get predatory mites so you can harness the natural mite control of these voracious insects.

What are Predatory Mites?

Look really close if you want to see these little guys, even though they are slightly larger than their prey. Mites are wingless insects with a solid one-piece body and no antennae. The predatory mites feed on spider mites and other pest mites as well as thrips and some other small insects.

In the absence of prey, predatory mites eat pollen and nectar and can revert to sucking plant juices. There are several varieties of predatory mites in the garden, each of which has a preferred food source. The mites have the same life cycle as the pest insects, starting with an egg stage, larval period, and finally a nymph stage.

How to Use Predatory Mites

First you need to know what your pest problem is. This may require some investigation and a magnifying glass to identify the culprit. Then choose the appropriate warrior to battle against the bad insect.

Western mites are effective against spider mites and two-spotted mites. The Phytoseiids are a group of predatory mites that overwinter in trees and are the most common of the insects. The stigmaeid or yellow mites are useful as predatory mite pest control against European red mites. Several of the varieties are commercially available for wide spread pest control.

Where to Get Predatory Mites

There is a practice among agricultural professionals called “seeding.” This basically means locating a tree or orchard with a population of the predatory mites you desire and relocating them. You do this by cutting a stem or limb from a tree infested with the beneficial mites and placing it where you want the insects to move in and feed on the bad mites.

The best time to harvest the insects for predatory mite pest control is spring. This is when plants are blooming and mite activity is at its peak. Some varieties of mites are also available online or through catalogues.

Encouraging Predatory Mites in the Garden

Spraying horticultural oil in spring can help reduce the mite population in areas that have a pest problem. The oil doesn’t usually bother the predatory mites, especially the phytoseiid variety, which overwinters in secluded and protected areas.

Use the least toxic pesticides for other varieties of insects and apply pre-bloom whenever you can to prevent killing the beneficial mites.

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Overall, the spider mites are one of the largest, most important and most destructive groups of pests in agriculture. Spider mites are less than 0.5 mm (1/50 inch) long, and adults can just be seen with the naked eye. The word “spider” in their name refers to their ability to spin webs. McDaniel spider mite is a prolific web spinner, twospotted mite is intermediate, and European red mite produces only a modest amount of webbing.

From formulating the plan to worker safety, pesticide regulations and REI times – This is the ultimate guide to integrated pest management. Learn how to effectively implement an IPM plan and use the right tools in the right way at the right time.

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Formulating a Plan

In this article you will learn how to control pests and improve the health of your cannabis plants using integrated pest management, commonly referred to as IPM. This involves a multi-point strategy – there is no quick fix, nor is there one solution that will wipe out all your pest problems. Proper pest management requires patience, consistency and determination.

It is important to understand that not all pesticides are bad. While many are incredibly harmful not only to pests, but also humans, in this article I will educate you about some of the safer alternatives to traditional pesticides. It is possible to safely control unwanted pests in your cannabis garden without harming yourself, your employees or the natural habitat around you.

Every cultivation facility should have a well-thought-out plan for their pest management program. This program should account for the prevention, and if necessary, eradication of: spider mites, russet mites, fungus gnats, root aphids, thrips and caterpillars. These are just a few of the more common pests you’ll find in a cannabis garden. There could also be many other less commonly known bugs, so you have to be vigilant in looking closely at your plants, and the soil, at all times. Complete eradication of a targeted pest can be difficult. Once a pest has established itself, decimating or decreasing the population will require an aggressive regimen that includes spraying daily to control populations and prevent other pests from getting established.

Spraying or applying pesticides to the foliage of plants isn’t the only way to control or eradicate pest populations. There are many other ways that you can minimize the spread of pests without the use of pesticides. In greenhouse and outdoor grows, growing specific types of plants around the cultivation area will attract both beneficial and predator bugs that will naturally control pest populations. Some plants that attract these bugs are: mint, peppers, and marigold. Beneficial and predator bugs, such as ladybugs, predator wasps and predator mites, can control unwanted pest populations in the area before they even have a chance to become a problem in your garden. Plants and flowers that attract bees, birds and insects will also create helpful bio- diversity, making it more difficult for the unwanted pests to thrive.

For indoor cultivation, it is imperative that you have your cultivation facility set up for a proper workflow. If you already have pests, you need to make sure you are not contaminating the rest of your facility when going from one area to the next. Make sure that you only go to contaminated areas at the very end of your day, and when you’re done working in that area, you must immediately exit the building. Do not ever walk back through the uncontaminated parts of your facility or the pests will spread quickly.

An aphid on a plant in a greenhouse

When most people think of pests in their cannabis garden they think of the more common varieties: spider mites, russet mites, aphids and thrips. However, there are also soil-dwelling pests that can exist, without your knowledge. These will decrease the health and vigor of your plants, without you even knowing they’re there, if you’re not careful to check for them. Some of the soil dwelling pests that plague cannabis plants are: root aphids, fungus gnat larvae and grubs. It is just as important to control the pests below the soil, feeding on your roots, as it is to control the pests that feed above soil on your plants.

Maintaining healthy plants is essential to controlling pest populations, both on the foliage and below the soil. Healthy plants will have an easier time fighting off pests than unhealthy plants. Plants have immune systems just like humans, and the stronger the plant’s immune system, the more likely it will be able to ward off pests and diseases. Allowing a plant to reach its full potential, by minimizing pests, means your plants will also have a better quality, smell and flavor, not to mention a bigger yield.

Worker Safety, Regulation and REI times

The application of pesticides requires certification from the state agricultural department. In certain situations, depending on the type of pesticide and method of application, a license may even be required. The application of pesticides without proper certification is against the law. Applying pesticides in a manner that is not in accordance with the label and instructions is also a violation of law.

The proper personal protective equipment (PPE) is required for anybody handling, mixing or applying pesticides. Employees can be a liability to your company if they are applying pesticides improperly. Make sure you and your entire staff are well educated about pesticide use requirements and limitations, prior to usage, and that only a properly certified person is handling the mixing and application at your facility.

The author, David Perkins, In his greenhouse after using insect killing soap.

After a pesticide is applied, you must abide by the re-entry interval (REI). This is the required time period limiting all workers from re-entry into areas where pesticides have been applied. This time period will vary depending on the type of pesticide used and the method of application. In some instances, pesticides applied in the last 30 days may require employee training before work can be done in those areas.

The misuse of or improper handling of pesticides is not only unlawful and dangerous to human health, but can also cause environmental damage to waterways and wildlife. The direct effects of pesticides on wildlife include acute poisoning, immunotoxicity, endocrine disruption, reproductive failure, altered morphology and growth rates and changes in behavior. Pesticides can indirectly impact wildlife through reduction of food resources and refuses, starvation due to decreased prey availability, hypothermia and secondary poisoning. Section 1602 of the California Fish and Game Code governs requirements for permitting of any project where pesticides will be used, and strictly regulates the disposal of all waste and run-off. It is imperative to know the regulations and to abide by them, or heavy fines will ensue!

Using Pesticides in a Regulated Market

Knowing which pesticides you can’t use, to avoid failing mandatory state testing, is just as important as knowing which ones you can use safely to pass required testing. Most states with regulated markets have strict limitations on the pesticides that can be used in cannabis cultivation. Pesticide use in the cultivation of cannabis is the most strictly regulated in the agriculture industry the pesticides allowed for use in cannabis cultivation are far more limited than any other crop.

Photo: Michelle Tribe, Flickr

Just because a product is certified organic does not mean that it can be used, or that it is safe to be consumed or ingested. Oftentimes when cannabis flower alone is tested it will not fail or show a detectable amount of pesticides or heavy metals. However, when that flower is turned into concentrates, banned substances are then detected in testing, leading to test failures.

Cannabis cultivation facilities that are located on land that was previously used for conventional agriculture, or located near vineyards or other agricultural crops that are heavily sprayed with harmful pesticides, run a very high-risk failing testing. This is because of either spray drift from nearby agriculture, or residual pesticides and heavy metals left in the soil from previous crops that were using pesticides banned for cannabis cultivation. Accordingly, if you’re going to be growing outdoors or in a greenhouse, it is imperative that you get a soil and water test prior to cultivation, so you can determine if there is any potential for test failures due to pesticides or heavy metals in the soil or water in that area.

Proper Application – Using the Right Tools in the Right Way at the Right Time

One of the most important factors in pest management is proper identification of pests and proper application and coverage of pesticides. It does not require an entomology degree to identify insects, these days there is a lot of information online that can help you identify cannabis pests. Proper identification of insects can make the difference between success and failure. With a good eye and a microscope, if you do your research, you can control most insects in your garden.

In order to control pests in your garden you must get proper coverage of the foliage of the plant when you are applying pesticides. There are different types of equipment that are commonly used to apply pesticides in cannabis cultivation: backpack sprayers, foggers, and airless paint sprayers are the most common. An alternative method involves using an automated dosing system such as a dosatron, which injects fertilizer or pesticides at a specific ratio into your water lines, allowing you to use only the exact amount of pesticide you need. That way you avoid wasting money on unused pesticides. It is also safer for employees because it minimizes employee exposure, since there is no mixing required, and it allows for a large volume to be sprayed, without refilling a tank or a backpack sprayer.

No matter what you are using you must ensure you get the proper coverage on your plants in order to control pests. The temperature and humidity of your cultivation area, as well as the PH and temperature of the pesticide solution, all factor into the success of your IPM. For example, PFR 97 needs to be applied at a higher humidity range, around 70% to be most effective. In some areas this is not possible so repeated applications may be required to ensure the application is effective. A high PH or alkaline PH can cause alkaline hydrolysis which will make your pesticide solution less effective and will dictate how long your pesticides remain effective after they are mixed. It is therefore important to use your pesticide solution as soon as you make it don’t let it sit around for long periods of time before use or it will be less effective.

In cannabis cultivation there are two different primary growth cycles: vegetative and flower. These cycles require different IPM strategies. In general, during the flowering cycle, pesticides should not be applied after the second week, with some limited exceptions i.e. for outdoor cultivation there is a longer window to spray since the flower set takes longer than a plant being grown inside, or in a light deprivation greenhouse, where there is a 12/12 flowering cycle.

Starting with an immaculate vegetation room is crucial to maintaining pest and mold free plants in the flowering cycle.

For the vegetative (non-flowering) cycle, a strict rotation of foliage spray applications targeting not only pests, but also molds and pathogens, will be necessary to avoid a quick onset of infestation. Starting with an immaculate vegetation room is crucial to maintaining pest and mold free plants in the flowering cycle. Preventative sprays that are safe for use include: safer soap (contact kill) for soft bodied chewing insects Regalia (biological control) for powdery mildew and PFR 97 (biological control) for soft bodied chewing insects. It is also helpful to spray kelp, which strengthens the cell walls of plants, making the plant healthier, and thus enabling the plant to better defend itself from pests and diseases. Also, Bacillus thuringiensis (Bt) is useful to prevent or kill caterpillars.

The best way to control a pest infestation in the flowering cycle is at the very beginning on day one. You must start aggressively, with a three-way control consisting of a contact kill and preventative during days 1-14 preventative and biological control during days 10-18 and then release predator bugs on day 25, for optimal results. Knocking back the population with an effective contact kill pesticide early on is essential to ultimately lowering populations throughout the grow cycle, so that you can spray a biological control to preclude them from returning, before you release the predatory bugs at the end of the cycle.

Biological controls can take anywhere from 3 to 10 days before they are effective. Biological pesticides are selected strains of bacteria or fungus. When the plant tissue is eaten by a targeted pest, the bacteria kills the pest from the inside providing control without having to spray pesticides repeatedly. Predator bugs are the last line of defense, used in late flowering. They can be used indoors, outdoors and in greenhouses. An example of a common predator bug is Amblyseius californicus used to control low populations of spider mites, but there are many different varieties and they are specific depending on the type of pest population you seek to control.

A common concern with the use of predatory bugs, is whether they will be present when the flowers are harvested. However, if there is no food for the bugs (i.e. pests) the predator bugs will leave in search of food elsewhere. Further, indoor predator bugs are usually very small in size and difficult to see to an untrained eye. It is very unlikely to see any signs of predator bugs near the end of the flowering cycle, or in the finished flower product. Even when using bigger predator bugs, the bugs will leave the plants when harvested and dried.

Having pests can be very stressful. It is not uncommon to have bugs, pests, rodents, animals and birds cause damage in cannabis gardens. Making an informed decision based on science and not on unproven assumptions can determine how successful you are at pest management. There are many factors that go into pest management and no one situation is the same. You must be dedicated and consistent pest management never stops. You will always have something ready to invade your garden. Prepare, plan, prevent and repeat!


Broad mites are occasional pests of coastal lemons from late July through early October infestations are enhanced by the presence of Argentine ants. This mite often occurs in conjunction with CITRUS RUST MITE, with the rust mite usually predominating in number. Populations of broad mite tend to be most severe in warm, humid conditions such as those found in greenhouses. No treatment thresholds have been developed for broad mite in citrus. If high and increasing numbers warrant a pesticide application, use miticides with the least toxicity to predaceous mites.

Common name Amount to use REI‡ PHI‡
(Example trade name) (type of coverage)** (hours) (days)
Pesticide precautions Protect water Calculate VOCs Decision support Protect bees
Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Always read the label of the product being used.
(Agri-Flex) 5.5–8.5 fl oz (OC) 12 7
RANGE OF ACTIVITY: Pests: broad (many insects and mites) Natural enemies: most
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
COMMENTS: Do not exceed a total of 17 fl oz of Agri-Flex or 0.047 lbs ai of abamectin-containing products or 0.172 lb a.i. of thiamethoxam-containing products per acre per growing season. Aerial application is not approved in California.
. . . PLUS . . .
(various products) 0.25–1% See label See label
RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites) Natural enemies: most
PERSISTENCE: Pests: short Natural enemies: short
MODE OF ACTION: Contact including smothering and barrier effects also improves translaminar movement and insecticide persistence.
COMMENTS: For use on all varieties. Certain formulations emit high amounts of volatile organic compounds (VOCs) use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2020. Review the Department of Pesticide Regulation’s updated fact sheet.
(Agri-Mek SC) 2.25–4.25 fl oz (OC or IC) 12 7
RANGE OF ACTIVITY: Pests: intermediate (citrus thrips, mites, leafminers) Natural enemies: predatory mites & thrips
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
. . . PLUS . . .
(various products) 0.25–1% See label See label
RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites) Natural enemies: most
PERSISTENCE: Pests: short Natural enemies: short
MODE OF ACTION: Contact including smothering effects also improves translaminar movement and insecticide persistence.
COMMENTS: For use on all varieties. Certain formulations emit high amounts of volatile organic compounds (VOCs) use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2020. Review the Department of Pesticide Regulation's updated fact sheet.
(Minecto Pro) 10–12 fl oz/acre 12 7
RANGE OF ACTIVITY: Pests: broad (many insects and mites) Natural enemies: predatory mites
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
(various products) 0.25–1% See label See label
RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites) Natural enemies: most
PERSISTENCE: Pests: short Natural enemies: short
MODE OF ACTION: Contact including smothering and barrier effects also improves translaminar movement and insecticide persistence.
COMMENTS: Do not exceed a total of 24 fl oz of Minecto Pro or 0.40 lbs a.i. of cyantraniliprole-containing products or 0.047 lbs a.i. of abamectin-containing products/acre per calendar year. Do not apply to nurseries. Aerial application is allowed only for citrus leafminer or Asian citrus psyllid.
(Envidor 2SC) See comments 12 7
RANGE OF ACTIVITY: Pests: narrow (mites) Natural enemies: predatory mites
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
COMMENTS: Application rate is 12 to 20 fl oz/acre (OC or IC) when horticultural spray oil is not used, and 18 to 20 fl oz/acre (OC or IC) when it is. Treatments without oil are more effective.
(FujiMite SC) 2–4 pt (OC or IC) 12 3
RANGE OF ACTIVITY: Pests: narrow (mites) Natural enemies: predatory mites
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
Label rates 24 0
RANGE OF ACTIVITY: Pests: narrow (mites and citrus thrips) Natural enemies: most
PERSISTENCE: Pests: intermediate Natural enemies: intermediate
MODE OF ACTION: Not available
COMMENTS: For use on all varieties. Apply as mites appear avoid applications during or preceding high temperatures (above 80ºF). Do not apply sulfur within 2 months of a previous oil spray or apply oil 60 to 90 days after a sulfur application.
** OC - Outside coverage uses 100 to 250 gal water/acre.
IC - Intermediate coverage uses 250-600 gal/acre.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for use on organically grown produce.
* Permit required from county agricultural commissioner for purchase or use.
1 Rotate chemicals with a different mode-of-action group number, and do not use products with the same mode-of-action group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a group number of 1B chemicals with a 1B group number should be alternated with chemicals that have a group number other than 1B. Mode-of-action group numbers (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

E.E. Grafton-Cardwell, Lindcove Research and Extension Center, Exeter and Entomology, UC Riverside

J.G. Morse (emeritus), Entomology, UC Riverside (emeritus)

D.R. Haviland, UC IPM and UC Cooperative Extension Kern County

B.A. Faber, UC Cooperative Extension Ventura County

Acknowledgement for Contributions to Insects, Mites, and Other Invertebrates

B.N. Cass, Entomology and Nematology, UC Davis

J. Gorden, Pest Management Associates, Exeter

H.M. Kahl, Entomology and Nematology, UC Davis

C.E. Kallsen, UC Cooperative Extension Kern County

D. Machlitt, Consulting Entomology Services, Camarillo

T. Roberts, PCA, Integrated Consulting Entomology, Ventura

J.A. Rosenheim, Entomology and Nematology, UC Davis

J. Stewart, Pest Management Associates, Exeter

P. Washburn, Washburn & Sons Citrus Pest Control, Riverside

Effective DIY Spider Mite Killer Recipes

You might be asking yourself, “What do spider mites look like?” Don’t worry if you’re at a loss because you cannot easily see them with the naked eye. You need a magnifying glass to be able to see these little pests.

Mature spider mites have eight legs, are typically red or black, and live on the underside of the leaves of plants. No one wants these annoying insects around. Follow our simple but effective home remedies to not only get rid of spider mites but also to kill aphids on plants and eliminate other pesky insects, as well.

Water, Water, Water – A Preventative Measure

At the beginning of the growing season, and maybe as often as every other week, use your garden hose as the first line of defense against spider mites. These insects tend to congregate in dusty plants or plants that are running low on water. Grab your garden hose and spray your plants every so often to keep them healthy and clean.

This extra step is especially crucial for your houseplants. You don’t want any spider mites to come inside and become houseplant pests, so take your houseplants outside periodically and hose them down as well.

Predatory Mites – The Most Natural Spider Mite Killer

There is a particular family of mites, the Phytoseiidae family, that are known to prey on spider mites. Specifically, you are looking for the Phytoseiulius persimilis, which we know about thanks to research done by the University of California. An individual predatory mite can eat up to five spider mites a day, helping to drastically reduce the reproductive potential of your infestation.

These natural predators will eat many different kinds of mite species and, even better, they won’t damage your garden, making these beneficial insects an excellent biological control method and integrated pest management (..). However, you only want to use this on your outdoor plants.

Neem Oil – An Easy DIY Spray for Spider Mites

Organic neem oil, one of the most pungent and useful pest control methods, is also one of the natural ways to save your infested leaves from further mite damage. Follow this recipe for a helpful DIY spray for spider mites.

Neem Oil Spray

Add the ingredients into a spray bottle and shake the bottle to mix. Use the oil spray on the entire plant. As the spider mites eat the section of plant coated with the homemade spray, they will die.

Repeat this process for your entire plant every couple of days until you begin to notice that the fine webbing is gone, meaning that the spider mites have been eliminated.

Alcohol Spray

Another easy DIY spray for spider mites is an alcohol spray you can make with things around the house. Follow the proportions and instructions below for an effective homemade spider mite killer.

DIY Alcohol Spray

Mix the ingredients in a spray bottle. Spray the mixture onto the leaves of the plant, particularly the underside of leaves.

The alcohol will kill the spider mites on contact. You will not want to use this if you have tried predatory mites, as the alcohol will kill them, too.

Insecticidal Soap – The Ultimate Homemade Spider Mite Killer

Insecticidal soap is an easy solution to kill spider mites. However, it is essential to know that insecticidal soap can also kill predatory mites, so if you have tried that pest control solution, then this will not be the choice for you. You can make this insecticidal soap with ingredients found around the house.

Homemade Insecticidal Soap

Pour the ingredients into a clean spray bottle and shake to mix. You want to spray the dish soap water mixture over the entire plant, including the stems and the underside of the leaves.

The composition of the dish soap will help dissolve the mites’ exoskeleton and make them more susceptible to dehydration and quick death. Be sure to test the water spray on a smaller section of the plant before continuing to the entire plant to make sure that the plant won’t have any adverse reactions.

If you want to pack an extra punch to your insecticide which will help deter future infestations from most garden pests, add two tablespoons of hot pepper powder to the solution. The capsaicin from the peppers works to prevent plenty of pests. Cayenne pepper and jalapeno pepper work best.

Rosemary Oil – The Best Spray for Spider Mites

If you want to harness the natural way that essential oils can be beneficial, use rosemary oil. Rosemary is a natural insecticide and using a concoction of rosemary oil and water will take care of your spider mite infestation. With a 2:1 ratio of water to rosemary oil, spray the oil spray onto the leaves of the plant to serve as a natural spider mite killer.

This oil spray is the best spray for spider mites if you have already used predatory mites because the rosemary oil will not kill them.

Horticultural Oil

If you have a garden full of fruit trees, then you might want to use horticultural oil. With fruit trees, you have to be extra careful because people will probably be eating the fruit.

By choosing a horticultural oil spray (especially a vegetable-based oil spray), you are keeping chemicals typically associated with pesticides away from your family.

When you apply the horticultural oil spray at the beginning of the growing season, the eggs that have lasted over-winter will become dehydrated, die, and fall off. This treatment will help your fruit trees start the season off mite free.

You can also continue to use a horticultural oil spray throughout the season against spider mites. The oil spray will coat the insects and suffocate them.

Because the life cycle of the spider mite is so short (roughly 20 days), they have a very rapid reproduction rate with females laying as many as 20 eggs a day. Hopefully, you found these various home remedies helpful in pest control endeavors.


If you have any friends or family who could benefit from this article of homemade spider mite killer tricks, please share on Facebook or Pinterest. Everybody deserves to have a beautiful, pest-free garden to call their own.

Watch the video: Spider Mite Circus