NC State Extension Publications

Description and Biology

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The minute oak bark beetle, Pseudopityophthorus minutissimus (Zimmermann), is also called the small oak bark beetle. It is tiny and dark brown. The male bores into the bark and excavates a short tunnel along the grain. He then starts two egg galleries across the grain from the central entrance burrow. By that time he is joined by one or two female beetles that extend the egg galleries. Eggs are laid and the newly hatched larvae mine in the phloem along the grain of the branch. The larvae are tiny, whitish grubs without legs. Minute oak bark beetles attack the branches on living, dying, and felled oak trees in the eastern United Sates. They usually do not infest the thicker bark on the trunk of oaks. The minute oak bark beetle infests trees that are stressed or dying or even dead branches on otherwise healthy oaks.

Side view of the minute oak bark beetle.

Side view of the minute oak bark beetle.

Top view of the minute oak bark beetle.

Top view of the minute oak bark beetle.

Face of the minute oak bark beetle.

Face of the minute oak bark beetle.

Antenna of the minute oak bark beetle.

Antenna of the minute oak bark beetle.

Fore tibia of the minute oak bark beetle.

Fore tibia of the minute oak bark beetle.

Rear view of the minute oak bark beetle.

Rear view of the minute oak bark beetle.

Host Plants

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Oaks seem to be the only host plants of the minute oak beetle. These beetles attack the branches on living, dying, and felled oak trees in the eastern United Sates. They usually do not infest the thicker bark on the trunk of oaks. Because the minute oak bark beetle primarily infests stressed, dying or dead branches, it is not a primary pest of oaks. The beetles could be considered an indication that something else has stressed the tree (for example, cutting down a tree probably stresses it greatly!).

Residential Recommendation

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By the time minute oak bark beetles are found in a tree, there is no use in applying an insecticide as the beetles are under the bark and out of reach. Pruning out dead wood, mulching, watering during excessively dry weather, and liming and fertilizing moderately according to a soil test will probably eventually control the beetles far better than applying an insecticide.

References

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For assistance with a specific problem, contact your local Cooperative Extension center.

This factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology & Plant Pathology

Publication date: Jan. 19, 2013
Revised: Oct. 4, 2019

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