Clover mites (Bryobia praetiosa) are tiny arachnids, related to spiders and ticks, not insects. They frequently become nuisance pests when they appear in large numbers around homes, especially those with lush landscaping. While primarily plant feeders, their seasonal movements often lead to sudden invasions of residential structures. This article details their physical traits and explains the environmental factors that trigger their movement indoors.
Physical Characteristics and Size
Adult clover mites are among the smallest house-invading pests, measuring approximately 0.75 to 0.85 millimeters in length (about 1/30th of an inch). They appear to the naked eye as tiny, reddish-brown specks that move slowly across surfaces. Their color varies from reddish-brown to a dark olive-green, particularly after feeding on vegetation.
A distinguishing feature is the arrangement of their eight legs. The first pair is exceptionally long, extending forward to roughly twice the length of the other three pairs. This elongated front pair is frequently mistaken for antennae. If a mite is crushed, it leaves a distinctive rusty-red stain on light-colored surfaces like walls or carpets. This stain is caused by the concentrated red pigment within the mite’s body, not blood.
Why Clover Mites Invade Homes
Clover mites are outdoor plant feeders, thriving on clovers, lawn grasses, and ornamental plants. Invasions are driven by environmental conditions and a search for protected shelter or egg-laying sites. They are cool-season pests, showing peak activity when temperatures are moderate, typically between 50°F and 75°F.
Mites begin migrating when outdoor temperatures become too extreme, such as excessive heat above 85°F or cold, wet conditions in late fall. They are strongly attracted to the sunny, warm sides of a building, like south and west-facing walls. Here, they congregate in preparation for dormancy or to find cracks for egg deposition. Their small size allows them to exploit minuscule gaps, sometimes as tiny as 0.15 millimeters, around window frames and foundations to gain entry. Clover mites are purely nuisance pests; they do not bite, sting, transmit diseases, or cause structural damage.
Safe Removal and Prevention
When clover mites are found inside, it is important to remove them without crushing them to prevent staining interior surfaces. The most effective indoor removal method is using a vacuum cleaner with a hose attachment to suction the mites from walls, windowsills, and curtains. Alternatively, a damp cloth or sponge can be used to wipe up the mites, which should then be rinsed in soapy water for disposal.
Prevention focuses on eliminating their access and preferred habitat adjacent to the foundation. An effective strategy is creating a vegetation-free buffer zone, typically 18 to 24 inches wide, around the home’s perimeter. This barrier should be maintained with bare, loose soil or covered with materials like pea gravel or coarse mulch, which mites struggle to cross. Sealing exterior entry points involves using caulk to fill small cracks and crevices in the foundation, window frames, and utility entry points.