Common Insect & Mite: Root weevils

Photo by: A.L. Antonelli

Use IPM (Integrated Pest Management) for successful plant problem management.

Biology Several species of root weevils can be serious pests of landscape plants including azalea, rhododendron, rose, and strawberry. The black vine weevil is perhaps the most common. Adult weevils create characteristic notchings along leaf margins of countless plant species. The weevil larvae also can be serious pests, particularly in nursery plants. The larvae feed on roots and in some cases girdle crowns and lower stems.

Management Options

• Apply beneficial nematodes which kill the larvae. They are used as a soil drench in moist soils over 52 degrees F (mid-fall in western Washington).
• Plant resistant varieties when available. Your county extension agent or WSU Master Gardeners can furnish a list.

Revision Date:5/6/2009

Adult control should begin when adults emerge late May-June or when first signs of notching appear on new leaves. A follow-up spray may be necessary about a month later. Beneficial nematodes can be applied to control the larval stage if soil temperatures are warmer than 52 degrees F.

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