It is time again for the annual migration of clover mites. These very tiny arachnids live and reproduce outdoors in the lawn, but they are only noticed when they migrate into dwellings by mistake. A mild fall last year, a mild winter, and an earl warm spring are all conspiring to bring on an abundance of clover mites, and clover mite complaints.
Clover mites are only 1/64th inch long. They are rusty brown to dark red, soft, oval, and flattened from top to bottom. When viewed with strong magnification you can see the distinguishing characteristic; very long front legs that extend forward as the mites crawl.
Clover mites are harmless. They cannot bite or sting; they do not carry diseases; they do not infest stored foods; they cannot attack the house structure and furnishings. They are an annoyance and nuisance because of their presence and tremendous numbers. Clover mites reproduce outdoors. Every mite seen indoors has wandered in from outside.
Clover mites are plant feeders only. They feed on sap from grasses and clover, and are especially numerous in lawns with a heavy growth of succulent, well-fertilized grass. They do not cause any apparent harm to turfgrass.
The traditional control for clover mites is to apply an insecticide spray as a chemical barrier around the house. Spray the foundation, the crevice between the foundation and the ground and the lawn for a distance of 6 to 10 feet out from the foundation. Successful chemical control requires a very thorough treatment. Materials labeled for this use include diazinon, Isotox, kelthane, and malathion. Application should be made as directed on the label and repeated after 2 weeks if mites persist.
Clover mites already indoors can be removed from surfaces with a vacuum cleaner. Avoid wiping the clover mites as crushing them often creates an undesirable and durable brown stain. Household insecticide sprays containing pyrethrins can be used for short-term, contact control of wandering mites.
This article originally appeared in the April 16, 1999 issue, p. 42.