| | Life history and Importance | Control
One of the first pests to become evident in the spring is the clover mite, Bryobia praetiosa. This species of mite is smaller than a pin-head and is dark red, rusty brown or olive green. It has eight legs, of which the front legs are rather long and characteristically extend forward from the body.
Life History and Importance
During the spring and summer months, clover mites are active at temperatures between 4°C and 24°C, feeding on the sap of many trees, shrubs, flowers and grasses throughout Alberta. They rarely become a nuisance out-of-doors, except occasionally on lawns.
In the fall, particularly during November and December, these mites migrate from their dwindling food supplies, sometimes in enormous numbers, to lay small, red, overwintering eggs in cracks and crevices on trees and buildings. Mites may be particularly heavy on the warmer, south-facing walls of buildings, and they may find their way indoors through cracks in walls and around doors and windows.
Overwintering eggs laid in the fall begin to hatch the following April and May, earlier if the weather is favorable, and houses are once again invaded by young mites in their search for suitable food plants.
Although short-lived and not harmful to people or household articles, large numbers of mites are a nuisance and leave red stains when crushed. They are more likely to be a problem in areas of newly established gardens or lawns, where there is a dense growth of succulent, well fertilized grass close to foundation walls.
Control
The first line of defence against clover mites is to seal off their entry points into the house, Caulking may be used around windows and weather stripping around doors. Cracks in foundations and walls should be filled.
The second line of defence is to keep the grass very short around the foundation, or preferably, to replace it with a 0.6 m wide strip of either bare soil or fine gravel (concrete is not as effective).
If this approach does not fit into your landscaping plans, there are pesticides available that will help through the peak migration period if the mite population is heavy enough to warrant control. These products should be applied as a spray to the outside walls, foundations and ground in a 4.5 to 6 m wide strip around the house.
The following pesticide is effective and available at most garden supply centres and some department stores: Malathion - 115 mL 50% EC/5L water.
One application should be sufficient, but if necessary, repeat treatment in 10 to 14 days.
For those mites already in the house, a spot treatment of a 0.5 to 1 % spray of propoxur around windows, doors, baseboards and other entry points can be used. An alternative method is to carefully vacuum infested areas in the house to remove the mites without crushing them and leaving stains.
Source: Agdex 622-5. Revised November 2004. |
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