Strawberry Root Weevils not only destroy strawberry plants but they can have a devastating effect on rhododendrons, raspberries and mint as well.
The cream colored larvae are about 6mm long and eat the roots of plants. The adults are brown and can range from 5-8mm long. They feed mainly at night and will notch the leaf margins of plants. To determine what is eating your plants, check out your garden at night with a flashlight.
The "c" shaped larvae of the Strawberry Root Weevil can do the most damage between March and May with the adults doing the majority of their damage in late May into early June. It's important to control the adults before they begin to lay eggs, which is about two weeks after they emerge as adults.
In general these pests do not kill most plants, but like with any infestation, a large population can quickly destroy a crop. The good news is, they are pretty easy to control.
- Apply beneficial parasitic nematodes to the soil in spring in the general area where you have had trouble with the Strawberry Root Weevil in the past. They can usually be purchased from a good quality local nursery or online from companies like GardensAlive!. They will kill the pests in the larvae stage.
- Mow strawberry plants down like grass in autumn to allow the sun to reach the crowns of the plants. Or better yet, rototill these plants into the soil and kill any existing larvae as you till the soil. Move your strawberry bed far away from the existing spot. This is why crop rotation is so important.
- At night, shake the plants over a large shallow box, such as a pizza box, and destroy any pests that fall into the box. They don't fly so you should have no trouble catching them. Dropping the bugs in soapy water or freezing them should kill them pretty quickly. Throw them away once dead, or add them to the compost pile.
- Planting alfalfa, clover, corn or wheat throughout your garden has been known to help repel these pests.
For more information and pictures of the Strawberry Root Weevil, check out this article from Oregon State University.