Accidental Invaders: Root Weevils Back »

Written collaboratively by Amanda Bachmann, Adam Varenhorst, and John Ball.


About Root Weevils

The latest insects to find their way inside South Dakota homes are the root weevils (Figure 1). Weevils (Family Curculionidae) are a kind of beetle (Order Coleoptera) that is characterized by a distinct snout on the front of their head, with antennae that originate halfway down the snout. Root weevils are members of the genus Otiorhynchus, and there are at least four species in South Dakota; the strawberry root weevil (Otiorhynchus ovatus), the rough strawberry root weevil (O. rugostriatus), the lilac root weevil (O. meridionalis) and the black vine weevil (O. sulcatus). The four species are very similar in appearance, size, and behavior.


Figure 1. Adult root weevil. Photo by Amanda Bachmann.
 

Behavior

Root weevil adults feed on many plants in the landscape but appear to prefer lilac leaves and yews in early summer. Their larvae feed on the roots of a variety of plants in the landscape. The mature larvae overwinter, pupate in the spring, and new adults emerge around June. Adult root weevils are approximately 1/3 of an inch long and are generally black in color. The adults do not fly, and will sometimes play dead if disturbed.

Management

Management for these weevils indoors is the same regardless of species. Since they do not feed or reproduce indoors, the best course of action is to sweep or vacuum them up. To prevent future invasions by the root weevils (or other insects seeking shelter inside) check around doors and windows for any possible entry points. These insects are considered nuisance pests indoors, and their presence could be an indication of a large outdoor population. To determine if plants around the home are being fed on examine them for “saw-toothed” leaf edges, which are characteristic of feeding due to these weevils.

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