The strawberry root weevil is a very common insect found throughout Iowa. The shiny black, hard-shelled adult weevils develop from larvae that live in the soil and feed on the roots of strawberry plants, evergreen trees and shrubs. In midsummer, the adults emerge from the soil. They feed on plant foliage but cause no significant damage to the plants. They would go unnoticed except that large numbers regularly wander into houses by mistake as accidental invaders. These are not damaging to the house or furnishings. They do not harm people or pets, and are a nuisance only by their presence.
Adult strawberry root weevils are brown to black and about 1/3-inch long. They have a pear-or light bulb-shaped body and long elbowed antennae. The wing covers are marked by many rows of small pits.
Combating strawberry root weevils in the house can be difficult and frustrating. Some of the invasion can be prevented by exclusion techniques that close their routes of entry. Look for and seal cracks and gaps in the foundation and around windows and doors through which the adults can crawl into the building. Spraying permethrin, malathion or other residual landscape insecticide on and along the foundation and in outdoor areas of weevil abundance may reduce the number of weevils outside and thereby reduce the number wandering in. Unfortunately, spraying of large areas (10-foot perimeters up to the entire lawn) and frequent reapplication may be required.
Adults already inside need only be vacuumed or swept up and discarded. Household aerosol insecticides are not very effective for controlling these weevils.
This article originally appeared in the 7/25/2003 issue.