Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
4/10/00
Contacts:
Donald Lewis, Extension Entomology, (515) 294-1101,
drlewis@iastate.edu
Elaine Edwards, Extension Communication Systems, (515)
294-5168, eedwards@iastate.edu
Yard and Garden Column for the Week Beginning April 14, 2000
Clover Mites
By Donald Lewis
Extension Entomologist
Iowa State University Extension
"Help! The south side of my house is covered with tiny red dots that don't appear to be alive until you stare at them and see them moving!" This recurrent springtime phone call is a sure sign that it is clover mite time, again.
Clover mites are widespread and occasionally very abundant. Most of us, mercifully, never know that clover mites are out there in our lawns and landscapes. They cause no damage, they are too small to notice and we just don't bother to go looking for them.
We don't have to look for them. These tiny mites, barely visible to the naked eye, have a knack for drawing attention to themselves. They attract attention through sheer numbers. We pay attention when they cover the side of the house and when they crawl indoors through gaps around windows and doors.
Wanderlust
When the weather conditions get just right, thousands (it only seems like millions) of mites begin a slo-o-o-o-w march through the landscape. This must be the arachnid equivalent of "wanderlust" as mass quantities of mites start crawling to a miniscule beat only they can hear.
Mites with no where to go and all day to get there wander aimlessly among the tangled grass blades of your lawn. By accident, they bump into the foundation of the house and begin climbing upward. The warm siding on the south side of the house seems to momentarily arrest their movement as they pause in the sunshine. A few press on and wander into the house. These you see on the countertops, windowsills, walls, curtains, cupboards or floor, assuming, of course, they are crawling on a light colored surface.
Description
It is difficult to describe something that is too small to plainly see but here goes. Clover mites are only 1/64th inch long (much smaller than a pinhead). They have a soft, oval body, which is flattened from top to bottom. They vary in color from rusty brown to dark red. They are eight-legged but the front two legs are very long and protrude forward at the head and look like antennae or feelers.
Clover mites live and reproduce outdoors. They feed on sap from grasses, clover and other plants but do not cause any noticeable injury.
In one of the rich ironies of life, clover mites are especially numerous in lawns with a heavy growth of succulent, well-fertilized grass. In other words, the better and nicer-looking your lawn is, the more likely you are to have large numbers of clover mites impatient to wander when the weather conditions are just right (sunny and warm, 50 to 75 degrees F).
Clover mite migrations usually happen in the early spring when warm temperatures first occur. Late autumn migrations also are possible.
Annoyance
Clover mites are an annoyance because of their presence and their tremendous numbers. Fortunately, they are harmless. They cannot bite or sting; they do not carry diseases; they do not infest stored foods; they cannot attack the house structure, furnishings or houseplants. Clover mites are only a temporary nuisance. They cannot reproduce indoors and each and every mite you see indoors has wandered in from outside.
The worst thing about clover mites is the reddish stain they leave if they are crushed. The stains are quite noticeable on white woodwork or walls and are difficult to wash away.
Controls
The most practical approach to a surprise visit by clover mites is to grin-and-bear-it. The problem is temporary, though off-and-on migrations may last for several days. Use a vacuum cleaner with proper attachments to effectively collect live mites without crushing them. Avoid wiping. Household insecticide sprays can be used to control wandering mites but the benefit is very short-lived.
The traditional control for clover mites is to prevent entry by applying an insecticide spray as a chemical barrier around the house. Spray the foundation and the lawn for a distance of 6 to 10 feet out from the foundation using a home lawn insecticide labeled for this purpose. Follow label directions. Repeat after 7 to 14 days if mites persist. Successful chemical control requires a thorough treatment with 2 to 4 gallons of spray for each 1,000 square feet. Such a treatment is laborious and you may prefer to hire it done.
Some authorities recommend removal of all grass, weeds and other vegetation from against the house foundation on the theory that an 18 to 24-inch wide bare strip will discourage clover mite migration. This technique is not always successful, as the clover mites may migrate over wood chip and rock mulches and through flowerbeds. As in most situations, there is no simple, one-size-fits-all, easy answer to this complex, real-world question.
ml: isugarden
Extension programs are available to all without regard to race, color, national origin, religion, sex, age, or disability.