Pest description and crop damage The Douglas-fir twig weevil is a small, wingless, grayish-black beetle with white markings and sometimes pinkish spots. The larvae mine under the bark or inside twigs. Infested twigs and small branches often turn a reddish-brown and die back. Small, stressed trees are especially susceptible to attack by the weevils, particularly in dry years.
Biology and life history The weevil overwinters as a larva or adult. The adult lays eggs in twigs in the summer. The larvae feed by mining just beneath the bark and pupate at the ends of the galleries the following spring. There is one complete generation per year.
Pick off adults if seen. Remove and burn infested twigs. Keep trees healthy with proper cultural practices, as healthy trees can better withstand insect damage.
No chemical controls listed.
See "Douglas-fir" in:
For more information
Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 60).