Predatory Mites

You may notice one while sitting on your patio enjoying your garden, or while digging in the soil to plant some flowers. A tiny, bright red bug is seen running rapidly (at least for its size) across the patio. Sometimes these may even be seen inside your home, and under close examination we see the telltale signs that it is a mite – 8 legs, no antennae. Without knowing more about it our inclination may be to squash this invader and feel that we probably have protected our plants or ourselves.

But, many of these large, bright red, fast moving mites are actually quite beneficial, and feed on other mites and on tiny insects and their eggs. There is one group that can be terribly annoying to us in their earliest life stage, and that is the ones called Chiggers, which do feed on mammals in their “larval” stage. But, even these become beneficial predators as they grow and become adult mites. We’ll discuss chiggers in more detail in a separate BugInfo article.

Another rather annoying large, red mite is the Clover Mite – Bryobia praetiosa. This species is a plant feeder, attacking lawn grasses, clover, and some garden plants, and when present in large numbers can cause noticeable damage. They are easily distinguished by their extremely long pair of front legs, which they hold straight out in front of them as they move. Their body is somewhat rounded or oblong and they have a deep red color. While they can damage plants and turf, the biggest complaint about Clover Mites is when they find their way inside your home, which they often do in the fall, looking for a protected place to spend the winter, or on hot summer days when they look to escape the heat. When thousands of these large mites are crawling across your floors and furnishings it can be quite frightening, and when smashed they will leave small reddish stains on the surface. Clover mites cannot bite and are harmless to humans, but annoying just the same.

The predatory mites can really be attractive arthropods. They have very long legs, a sign that they are fast moving and capable of capturing their prey. They have very hairy legs and various shades of red and orange. Several species are raised commercially and sold as a biological control for other mites that feed on your plants, such as spider mites. It would be normal to find these as solitary individuals, either on your plants or in your home. If you have a problem with mites feeding on your plants you may find many of the predatory mites there too, but they will stand out as obviously different from the plant parasites, and will be feeding on them. If you do happen to find these on your plants, or purchase some for this use, be careful to leave them alone to do their thing. You should not apply any other products to the plants to kill the damaging mites, as this will also kill the beneficial kinds.

Many of these predatory mites are native animals in regions of North America, and can be fairly successful in controlling populations of damaging mites such as spider mites, rust mites, or red mites that are found in fruit orchards. To be successful the predator needs to prefer to feed on the pest mites and to actively look for this food, which predatory mites in the family Phytoseiidae do very well. So, before you kill it try to learn about it, and you may just be helping your garden by leaving these helpful mites alone and alive.