Clover Mites May be Showing up in Homes Now
Clover mites (Byrobia praetiosa) are active in the spring and fall months. They can be pests of many types of plants, including turf, and can occasionally invade homes. Typically they are active from February through May until hot temperatures force them to lay eggs that will over-summer in protected exterior places. Once temperatures decline in fall, the eggs hatch and a new generation of mites will emerge. The fall generation can remain active until winter.
Clover mites feed in a meandering pattern, which is evident by the damage on the leaf of a plant. Feeding on grass blades results in a silvery appearance, especially just prior to turf death. (Images from Bugwood.org)
Clover mites are roughly the size of a pinhead and are described as moving dark spots. They can range in color from dark green to dark brown, sometimes with a dark red appearance. Their front legs are elongated, about twice the length of the other legs. Eggs are tiny, round, and red in color. Other mites and arthropods that could be misidentified as clover mites include other spider mites, Banks grass mite, predatory mites, bird/fowl mites, and springtails.
Clover mites can injure many plants, but symptoms are most commonly seen on turfgrass, particularly in the spring months. Symptoms resemble drought-stress and show up on areas of the lawn that are particularly dry and sunny. Close inspection of grass blades shows silvery streaks. During severe infestations, patches of turf can be killed.
In Utah, clover mites are more common as an indoor nuisance pest, particularly in the fall when mites seek refuge from the cold. In the late winter or early spring, warming temperatures stimulate mite activity, particularly inside, or on south or west-facing sides of buildings. Mites may seem to appear out of nowhere if they are prompted to migrate by cutting their host plant; an increase in heat or heavy rain; or a change in seasons. Clover mites are not a pest of health concern and do not bite.
Controlling clover mites is best accomplished by habitat modification. Outside, clover mites can be reduced by the following:
- Focus control efforts on the south and west sides of buildings where clover mites are most likely to live and enter the home.
- Create a 1.5 to 3 foot wide vegetation-free zone around the foundation exterior.
- Use supplemental water to water-stressed areas of the lawn.
- Plant plants that are unattractive to clover mites, such as geranium, chrysanthemum, zinnia, marigold, salvia, rose, petunia or shrubs such as barberry, juniper and yew.
- Apply insecticides to turf within 10 feet of the foundation (e.g., bifenthrin or lambda-cyhalothrin).
Indoors, mites only survive a few weeks, so they may be tolerated in low numbers. If present, vacuum the area and dispose of the bag. Never crush clover mites because they can stain fabrics. To prevent them from entering the home, seal exterior cracks and crevices, especially around windows. and doors
- Ryan Davis, Arthropod Diagnostician
Cranshaw, W.S. Clover and Other Mites of Turfgrass. Colorado State University Fact Sheet No. 5.505.
Gomez, C., and Mizell, R.F. 2008. Featured Creatures: Clover Mite (Bryobia praetiosa Koch). University of Florida, No. EENY-437.