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Minute oak bark beetle

Pseudopityophthorus minutissimus[4]

The minute oak bark beetle is a tiny, dark brown bark beetle that breeds under the thin bark of stressed, dying or dead oak branches; it isn't a primary pest of oaks, but it is one of the beetles that can carry the oak wilt fungus between trees.[1][2][3]

Group
Insect
Order
Coleoptera
Family
Curculionidae
US records
7 states
Sources
4 cited
Updated
2026-10-19

No licensed photo of this species is available yet; the identification notes below describe what to look for.

On this page
  1. Identification
  2. Where it lives
  3. Biology
  4. Damage and signs
  5. Health risk
  6. Control
  7. Related profiles
  8. Common questions
  9. Sources

How to identify it

  • Adults are tiny, dark brown bark beetles; the larvae are tiny, legless, whitish grubs.[1]
  • Under the bark, a short entrance tunnel runs along the grain with two egg galleries branching across the grain from it, and larval mines run back along the grain.[1]

Where it lives

It attacks oaks in the eastern United States and has been studied as far west as Minnesota, Missouri and Wisconsin.[1][2][3]

US map: public records from 7 states since 1990 (GBIF).

Biology and life cycle

A male bores into the bark and starts the galleries, and one or two females join him to extend them and lay eggs.[1]

It infests branches of living, dying and felled oaks, usually not the thick bark of the trunk, and prefers stressed, dying or dead branches, even on otherwise healthy trees.[1]

In a Minnesota study, flight peaked in mid-May, and branches of trees killed by oak wilt were commonly colonized.[2]

Damage and signs

  • Because it mainly attacks stressed, dying or dead branches, it is not a primary pest of oaks.[1]
  • Oak bark beetles, including this species, can move the oak wilt fungus from tree to tree; they are considered important vectors in Missouri and Ohio, though only 4 to 13 per 1,000 beetles carried the fungus in Minnesota, where their role was judged minor.[2][3]

Health risk

It bores only into oak bark; NC State, the Forest Service study and Wisconsin Extension mention no risk to people.[1][2][3]

Control

Prevention

Prune oaks only during the dormant season, when sap and bark beetles aren't active, and promptly remove oaks killed by oak wilt so beetles can't pick up the fungus.[3]

Pesticides

Insecticides are no use once the beetles are found, because they are already under the bark and out of reach.[1]

Common questions

Do minute oak bark beetles kill oaks?
Not by themselves; they breed in stressed, dying or dead branches. Their bigger significance is that they can carry the oak wilt fungus.[1][2][3]
When should I prune oaks to avoid oak wilt?
In the dormant season, when sap beetles and bark beetles that can spread the fungus aren't active.[3]

Sources

  1. NC State Extension, “Minute Oak Bark Beetle (PDIC Factsheet).” content.ces.ncsu.edu/minute-oak-bark-beetle (accessed 2026-10-19)
  2. USDA Forest Service, Treesearch, “Flight periodicities, phoresy rates, and levels of Pseudopityophthorus minutissimus branch colonization in oak wilt centers (A. K. Ambourn, J. Juzwik and J. E. Eggers, Forest Science 52, 2006).” research.fs.usda.gov/treesearch/18409 (accessed 2026-10-19)
  3. University of Wisconsin-Madison Extension, Wisconsin Horticulture, “Oak Wilt.” hort.extension.wisc.edu/articles/oak-wilt/ (accessed 2026-10-19)
  4. iNaturalist, “Pseudopityophthorus minutissimus taxon page (order and family).” www.inaturalist.org/taxa/229124 (accessed 2026-10-06)

Updated 2026-10-19. Built from sourced records. Spot an error? Tell us.