Managing Clover Mites
by Barb Ogg, PhD, Extension Educator
Clover mites are common nuisance pests in Nebraska, often invading structures in enormous numbers. These tiny pests are most troublesome in spring and again in fall. They may appear on window sills or inside sliding glass doors during the winter months on warm sunny days. Clover mites often invade buildings near areas where the sun is warmest; many people report invasions on the south or southwest side of the building
The clover mite is not an insect but is an eight-legged relative of spiders and ticks. The full-grown clover mite is slightly smaller than a pin head and has a reddish-brown body. Under magnification (Figure 1), you will note they have an unusually long pair of front legs, which distinguishes them from other mites. They appear as brick-red specks crawling around windows, drapes, curtains and furniture.
Clover mites do not damage buildings and furnishings, nor do they injure humans and pets.
Clover mites feed by sucking sap from various plants. They feed on clover, lawn and other grasses, various trees, ornamental plants and shrubs, but do not cause much damage. High numbers are often associated with maintained and well-fertilized lawns. These mites are so tiny, they readily invade homes by entering through cracks around windows, doorways and other entry points.Life History
In Nebraska, there are at least two generations of clover mites each year, invading homes in the fall and spring when temperatures are moderate.
Clover mites are usually inactive during summer and winter.
Clover mites lay tiny, reddish eggs (Figure 1) under tree bark, in cracks of fence posts or foundation walls and other protected locations. Eggs laid in the late spring lay dormant in the hot summer and hatch in the fall. After hatching, immature clover mites begin to feed on plant juices and pass through their life cycle (two immature stages and adult) over the course of a month. These adults lay eggs which overwinter, but all stages of clover mites may be present in the wintertime. In the spring, overwintered eggs hatch and immature mites move to find food plants, molt and pass through two nymphal stages. This spring generation is usually a bigger problem for homeowners than the fall generation.Management Strategies
OUTDOORS -- Effective control means preventing entry into buildings in the spring or the fall. The best way to prevent entry is to remove grasses and weeds in a three-foot strip around foundations, although mites may cross mulch and pea gravel to enter the home anyway.
Some flowers and plants are not attractive to clover mites. If these plants are located near the house, it may serve as a barrier to mite movement from the lawn into the building. Some unattractive plants include: petunia, salvia, geranium, chrysanthemum, rose, zinnia, yew, arborvitae, juniper and spruce.
A chemical barrier outside the home may help reduce or prevent infestations inside the home. Treat 5-10 feet out from the base of the foundation and a few feet up on the walls. Successful chemical control requires a very thorough treatment and may need to be repeated because many products on the market registered for clover mite control tend to be short-lived. Treat when daytime temperatures will be at least 60 degrees F because chemical effectiveness may be reduced with cooler temperatures.
Some common names for chemicals registered for exterior control of clover mites in Nebraska include permethrin, tralomethrin, cyfluthrin, tetramethrin, malathion and chlorpyrifos. Kelthane is an acaricide with more specific activity against mites. It can be used outdoors only on ornamental grasses or other plants. Refer to the pesticide label for more complete locations where products can be used.
INSIDE -- Clover mites inside are best controlled with a vacuum cleaner. Avoid crushing or smearing the mites, especially on fabrics, because they may leave a red stain. It is not recommended to use chemicals indoors for clover mites. A vacuum cleaner works just as well and eliminates pesticide exposure.
Whitney Cranshaw, Colorado State University entomologist, suggests putting a fine layer of dust around windows, in cracks and other areas where clover mites may enter. Try using talc-containing baby powder, diatomaceous earth and even baking soda. The mites coated with the fine dust will die in the barrier.
Clover mites are so tiny they stick easily to almost any type of sticky tape. Place double-sided masking tape on window sills or other areas where mites are entering to catch the tiny mites as they cross the tape (Figure 2). When the tape becomes filled with mite bodies, simply peel it up, throw it away and replace, if needed.
- READ, UNDERSTAND AND FOLLOW ALL PESTICIDE LABEL DIRECTIONS AND PRECAUTIONS.
- Keep all pesticides in their original containers.
- Do not allow anyone near treated surfaces until dry, and keep all pesticides out of reach of children and pets.
- Do not contaminate food and water.
Sources: Clover Mites and Their Management, S. Kamble, University of Nebraska; Clover Mites in the Home, W. Cranshaw, Colorado State University; Clover Mites, D. Lewis, Iowa State University.
- Figure 1: James Kalisch, Department of Entomology, UNL
- Figure 2: Barb Ogg, UNL Extension in Lancaster County
University of Nebraska-Lincoln Extension in Lancaster County is your on-line insect pest and wildlife educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office