WSU Extension

Hortsense

Yew
 
Insect
Cottony camellia scale 
Lecanium scale 
Root weevils 



print version| pdf version| email url    
Caption: White pine weevil damage on spruce
Photo by: C.G. Landgren
  
Yew : Root weevils
(revision date: 2/14/2019)


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


Non-Chemical Management
  • 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 degrees F (mid-fall in western Washington). Read and follow the label directions carefully.
Select non-chemical management options as your first choice!

Chemical Management

Adult control should begin when adults emerge late May-June or when first signs of notching occurs 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bayer Advanced Power Force Multi-Insect Killer R-T-S
    Active ingredient: cyfluthrin  |  EPA reg no: 72155-39
  • Bonide Systemic Insect Control
    Active ingredient: acephate  |  EPA reg no: 239-2461-4
  • Naturalis L
    Active ingredient: Beauveria bassiana  |  EPA reg no: 53871-9
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • This list may not include all products registered for this use.
Images

+ Show larger images

 
Caption: White pine weevil damage on spruce
Photo by: C.G. Landgren
Caption: Black vine weevil adult and leaf damage
Photo by: A.L. Antonelli