Strawberry: Root weevils

Biology

Several species of root weevils are common pests of strawberries. Adults are typically brown to black in color and may have lighter markings on the back. They range in size from 1⁄5″ to 1⁄3″ in length. These beetles cannot fly. Adults cause minor damage to plants by chewing ragged notches in the leaf margins. However, the most serious damage is done by the larvae. They are curved, legless, and white or pinkish with darker heads. They are found in the soil, where they feed on the roots. Severe root damage can occur, resulting in wilting and death of plants. Root weevils generally overwinter in the soil as larvae, with adults emerging in spring to early summer. Root weevil adults typically feed at night and spend the day at ground level.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

• Hand-pick and kill night-feeding adults, when practical.
• Cultivate future planting sites in the fall to reduce numbers of overwintering root weevils.
• Control weeds in and around plantings. Weeds may serve as other hosts for root weevils.
• Heavily damaged plantings should be destroyed.
• Beneficial nematodes may be purchased at some garden centers. They are only effective if soil temperatures are warmer than 53° F. The soil must be moist prior to application and for several days afterward. Do not apply nematodes in direct sunlight, since ultraviolet light quickly kills them.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Apply at night when adult weevils are feeding.
• Use a flashlight at night to determine where this activity has begun.
• Entomophagous nematodes (available through some nurseries) have proven useful. Nematodes are sensitive to UV light.
• Do not apply in direct sunlight. Apply nematodes only in late summer or early fall to very wet soil when soil temperatures are above 52° F.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

• Azera Gardening [Organic]
  Active ingredient: azadirachtin, pyrethrins [EPA registration number: 1021-1872]
• Bonide Eight Insect Control Yard and Garden R-T-Spray
  Active ingredient: permethrin [EPA registration number: 4-407]
• EcoGarden [Organic]
  Active ingredient: azadirachtin [EPA registration number: 71908-1-81268]
• This list may not include all products registered for this use.

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