Our two perennial household accidental invaders of mid-summer are active now, causing annoyance and discomfort for invaded home owners. The strawberry root weevil (SRW) and imported longhorned weevil (ILHW) are well- known pests of summer. Both are approximately 1/4 inch long with long antennae and legs. They have a small narrow thorax and head, and a large, globose abdomen, thus having a body shape roughly the same as an incandescent light bulb (at least that~s how Dick McClure, Fremont County Extension Director, described it!). The SRW is shiny black to blackish-brown; the ILHW is mottled grayish- tan.
Both weevils are commonly found throughout Iowa. They develop from larvae that live in the soil and feed on the roots of strawberry plants, evergreen trees and shrubs. In mid-summer, the adults emerge from the soil and live for about a month. They feed on plant foliage but cause no significant damage to the landscape plants.
They do, however, wander into homes by accident, often in enormous numbers. They may be found singly or in groups just about anywhere in any room. They are harmless and do not damage the house or its furnishings. They do not harm people or pets, and are a nuisance only by their presence.
Managing strawberry root weevils is difficult and frustrating. Try sealing cracks and gaps in the foundation and around windows and doors where the adults can crawl into the house. Spraying malathion, diazinon or Dursban insecticide on and along the foundation and in outdoor areas of weevil abundance may be of some benefit. It has been reported that SRW can be trapped outside by placing pans of water along the house foundation. The weevils are attracted to the water, fall in the containers and drown. Empty the water traps frequently to eliminate breeding sites for mosquitoes. In theory, trapping or spraying may reduce the number outside and thereby reduce the number wandering in.
Adult weevils already inside the house need only be vacuumed or swept up and discarded. Household aerosol insecticides are not very effective for controlling the weevils but could be used directly on the insects to kill them for easier disposal.
This article originally appeared in the July 15, 1992 issue, p. 124.