WSU Extension


Caption: Bark beetle larval galleries
Photo by: A.L. Antonelli
print version| pdf version| email url    

Elm : Bark beetles
(revision date: 6/23/2015)

Elm bark beetles are about 1/8" long and may be shiny brown or black. Adults, larvae, or pupae overwinter under bark. Adult beetles emerge in the spring (around May), leaving tiny "shotholes" in the bark. Adults feed on the young bark of elms, occasionally girdling and killing twigs. After feeding, the adult beetle lays eggs in galleries under the bark of branches, trunks, or in branch crotches of diseased or weakened trees. Adults will also lay eggs in recently cut wood when the bark is intact. The galleries are typically parallel to the grain of the wood, with the larvae making secondary galleries more or less perpendicular to the main gallery. Beetles emerging from trees infected with Dutch elm disease will infect the trees they attack.
Management Options

Non-Chemical Management
  • Maintain plant health. Healthy plants are less susceptible to infestation. Select the proper plant for the site and provide proper cultural care.
  • Remove damaged or infested limbs in spring before adult beetles emerge. Also remove dead or dying trees. Remove and destroy bark from freshly cut wood, or burn or bury wood.
  • Avoid injury to trees, especially during spring and summer. Adult beetles are attracted to wounds.
Select non-chemical management options as your first choice!

Chemical Management

None recommended.

    - hide images

+ Show larger images

Caption: Bark beetle larval galleries
Photo by: A.L. Antonelli
Caption: Shothole borer galleries
Photo by: E.H. Beers
Caption: Bark beetle (very similar to shothole borer)
Photo by: A.L. Antonelli