Yew: Root weevils

• Categories: Conifers Ornamentals Yew Yew Insects
• Last review date: 2025-08-21 04:53

Biology

Root weevil larvae feed on the roots and bark of plants near the crown. The white grubs are found in the soil around the roots. Larval feeding can cause significant damage, sometimes resulting in girdling of roots or crown and causing decline or death of the plant.

Adult black vine weevils (one species of root weevil) may feed on yew foliage but cause little damage. Symptoms of adult feeding include needles that are notched or cut off.

Adult root weevils range in size from 1⁄4″ to 1⁄2″ long. They are brownish to black, flightless beetles which climb into the foliage to feed at night.

Management Options

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

Non-chemical Management

Select non-chemical management options as your first choice!

• Hand-pick and kill night-feeding adults when practical.
• Apply beneficial nematodes which kill weevil larvae. The nematodes are used as a soil drench in moist soils over 55° F (mid-fall in western Washington). Read and follow the label directions carefully.

Chemical Management

• Adult control should begin when adults emerge late May-June or when first signs of notching occur in spring.
• Homeowners should not make foliar applications to trees over 10 ft tall.
• Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.

• Safer Brand BioNEEM Multi-Purpose Insecticide and Repellent Concentrate [Organic]
  Active ingredient: azadirachtin
  EPA registration number: 70051-6-42697
• This list may not include all products registered for this use.