Pit scale
Asterolecanium spp.
50 host plants
Last updated
You will see small pits or depressions in oak bark created by scale insect colonies feeding beneath the bark surface. Pit scales are tiny and reddish. Heavy infestations create visible bark damage and pit scarring. Quercus species are susceptible. Damage is primarily cosmetic, with minimal impact on tree health.
No chemical control is warranted for this primarily cosmetic pest. Pit scale damage does not threaten oak health. Prune heavily scarred branches if appearance is important. Dormant oils may reduce populations if aesthetic concerns justify treatment. Natural enemies including parasitic wasps and mites control many populations. Maintain tree vigor.
Quick Reference
Cultural Controls
- Prune out and destroy severely infested twigs to help control localized infestations (when practical).
- Provide proper culture.
- Healthy trees are more able to tolerate insect damage and are more disease-resistant.
- Natural enemies may help control scale populations.
- Avoid use of broad-spectrum insecticides which kill beneficial insects.