A globe trotting plant pest, spider mite occurs in every temperate region in the world, troubling a wide range of plant life from vegetables and ornamentals to houseplants and cut flowers to cannabis. There are more than 1200 species in the spider mite family but by far the most common one in homes and greenhouses is the two-spotted spider mite, Tetranychus urticae.
An adult two-spotted spider mite is about 1/50 of an inch long, making it nearly impossible to see any detail with the naked eye. Under magnification, however, you’ll see a beige body with what looks like dark spots on either side of its dorsal section. Nymphs and eggs both look slightly different, but as with most plant pests, magnification is crucial to be 100% sure of what you’re seeing. Cell phones are great for this task—just use the camera app and zoom in like you’re going to take a photo. A magnifying glass works too, if there’s one handy, or a jeweler’s loupe that can be worn on a lanyard.
Determining If It’s A Spider Mite Problem
Damage from spider mites typically appears as small yellow or white spots on the leaves, resulting from the pest feeding on the plant. After feasting on the plant sap, spider mites leave behind what people often describe as webbing on the leaves and stems. This webbing is prolific and looks like a fine, silky substance over the entire plant surface. In addition, once populations reach concentrated levels the spider mites begin to fortify their territory by producing even more webbing, allowing them to traverse the plant with greater ease. If you see this occur you can be sure there are spider mites in the area, as no other common plant pest produces webbing in such a manner.
There are several reasons why spider mites appear on plants. They can easily be brought into a home on propagated plant material or soil, or they can enter through open windows or doors. Spider mites look for warm, dry conditions in a home which cause plant stress. Likewise, they can be brought into a greenhouse on employees’ clothing, propagated material, or through the air on small strands of webbing the mites use as sails to distribute on wind currents.
Populations of spider mites can be measured best in levels on a scale of low to high. At the lowest level, one or two individual adult or nymph mites appear on a leaf with minimal damage observed. At the medium level larger populations can be seen on a leaf, made up of all life stages (egg, larva, nymph, adult) with more obvious damage symptoms. At the highest level the plant is a full breeding ground complete with webbing, significant plant damage, and all stages of the spider mite’s life cycle present.
Predatory mite Neoseiulus californicus ^
Getting Rid Of Spider Mites
There are many approaches for effective spider mite control but the method of choice largely depends on the variables that are unique to your plants. In general, to get rid of an established population of spider mites on plants, introduce beneficial insects that are natural enemies of spider mites. These include predatory mites like Spidex (Phytoseiulus persimilis), Spical (Neoseiulus californicus), and predatory gall midges Spidend (Feltiella acarisuga).
Spidex is an excellent predator of spider mites as it feeds exclusively on this pest. A voracious predatory mite, it can easily traverse the plant. When introduced preventatively or in great numbers, Spidex eventually eats every spider mite on a plant. It feeds on all stages of spider mites with a preference for eggs. In some cases two to three applications, approximately five to seven days apart, are necessary to get spider mites under control.
•Spidex Vital PLUS Sachets
•Spidex Boost Sachets
•Spidex Vital GO Sachets
•Spidex Vital Bottle (for large area applications)
Spical is another beneficial species that feeds on two-spotted spider mites and other species in the spider mite family. It’s tolerant of various temperatures and lower humidity but works best under warm to hot conditions. It develops at the same temperatures at which the two-spotted spider mite, its principal prey, develops.
•Spical Ulti-Mite Sachets
•Spical PLUS Sachets
•Spical Bottle (for large area applications)
Spidend is especially useful for hotspot treatment. After emerging from the pupa stage, adult predatory gall midges actively search for spider mite colonies and deposit eggs next to the spider mites. Once they emerge, the larvae feed on the spider mites. This product comes in a plastic cup: a hole is placed in the lid and the cup is set on the rock wool slab or directly on the soil. Spidend is used in combination with Spidex Vital.
•Spidend Plastic Cup
Spidex (Phytoseiulus persimilis) ^
A Note About The Packaging
Sachets usually allow predators to continuously reproduce and emerge onto the canopy for three to five weeks. Koppert sachets are designed with custom-made mylar that retains humidity much better than the typical teabag-style sachets that dry out quickly. Each sachet is like a mini birdhouse for beneficials, allowing them to produce two or three more generations and lasting for weeks. That amounts to more bugs for your buck!
Sachets are especially useful for containers and hanging baskets where infestations can develop out of sight in hidden nooks and crannies. For larger deployments in greenhouses and fields, products are available in volume in bottles or buckets for shake-on or mix & spray applications.
Preventing Spider Mites II: The Sequel
If you’ve dealt with spider mites in the past and do not want to deal with them again, our Spical Ulti-Mite sachets are the best option. They’re great to use preventatively or at the first sign of spider mite damage. Adult predatory mites, nymphs, and larvae vigorously search for and prey on spider mites. Again, the approach you choose depends on your growing situation.
Spical combined with predatory mite Spidex can control spider mite colonies and hotspots. In any event, constant scouting is also essential to be aware of the pest and beneficial population numbers on houseplants, cut flowers, veggies and ornamentals, or cannabis.
While the decision to purge spider mite infected plants rests with the grower alone, our expert team at Natural Enemies can provide guidance and explain all of the available options.
An integrated pest management (IPM) strategy can help keep spider mites under control while implementing effective practices to prevent them from appearing again. We are happy to help you on your journey to a pest and pesticide-free growing environment! If you’d like further assistance in finding the right products for you, please contact our customer service team. Call us during normal business hours at (503) 342-6698 or message us through our live chat (with an actual person) for customized service.
DEEPER DIVE
Spider Mites and Other Mites
https://www.koppertus.com/plant-pests/spider-mites-and-other-mites/
The Various Stages of the Spider Mite
https://www.koppertus.com/news-information/news/the-various-stages-of-the-spider-mite/
DEEPER DIVE
Two-Spotted Spider Mite
https://www.koppertus.com/plant-pests/spider-mites-and-other-mites/two-spotted-spider-mite/
Ten Facts About Spider Mites
https://www.koppertus.com/news-information/news/2021/default-e9513f06ba/
Spider Mite Control: The Essential Guide
https://www.koppertus.com/knowledge/spider-mite-control-the-essential-guide/#introduction
Biocontrol for Spider Mites
https://www.koppertus.com/news-information/news/2019/biocontrol-for-spider-mites/
