Ash Bark Beetle (Western)
Ash bark beetle galleries (Swiss Federal Institute for Forest, Snow, and Landscape Research, Bugwood.org)
- adults: ~ 1/6 inch long; dark with white to yellow scales; clubbed antennae
- larvae: white grubs with no legs and a brown head capsule
Host Plants, Diet & Damage
- feed on sapwood and phloem layers under the bark
- typically attack smaller branches, but can attack the trunk
- prefer highly stressed trees
- leaves above the damaged areas will turn color and die
- if the main stem is attacked, tree death may occur
- create small round holes in limbs
- galleries can be found under bark
- can introduce fungal pathogens
Biology, Life Cycle & Damaging Life Stage
- overwinter as late-stage larvae under the bark or as adults in bark notches
- larvae and adults become active in mid- to late-spring
- adults mate and eggs are laid within a gallery that encircles and girdles the branch
- larvae hatch and burrow outward from parental gallery
- typically one generation per year
- adults and larvae damage limbs and occasionally the main stem
- Control is generally not warranted.
- Remove and discard infested branches prior to beetle emergence.
- Reduce stress on ash trees.
- Apply insecticides (carbamates; pyrethroids) to the bark and branches to prevent damage to susceptible trees in areas of active ash bark beetle activity.
For more information, see our Bark Beetles fact sheet.