Xyleborus affinis

From Bugwoodwiki

Authors: Van Driesche, R.G., J.H. LaForest, C.T. Bargeron, R.C. Reardon, and M. Herlihy. 2012. Forest Pest Insects in North America: a Photographic Guide. USDA Forest Service. Forest Health Technology Enterprise Team. Morgantown, WV. FHTET-2012-02.

Hexapoda (including Insecta)
U. affinis
Scientific Name
Urophora affinis
(Frauenfeld, 1857)
Common Names
knapweed gall fly, banded gall fly, seed-head gall fly

Orientation to Pest

Xyleborus ambrosia beetles are a genus of wood-boring beetles that carry fungi that colonize their galleries and serve as food for their larvae. Other genera of beetles that have similar symbiotic relationships with fungi are also referred to as ambrosia beetles. The genus Xyleborus appears to be a collection of poorly related beetles that is in need of revision. As currently constructed, there are at least 17 species in the United States and Canada (16 in the eastern United States), mostly native but with several invasive species. Many of these species breed in both coniferous and deciduous trees and shrubs of all sizes. Trees preferred for attack are ones that are unhealthy, dying, or that have recently been wounded or felled. Dead areas in living trees can also be attacked. Because this group of beetles inoculate their larval galleries with wood-decay fungi, which are eaten by their larvae, these beetles are able to make their larval galleries in heartwood (a zone of low nutrition), in contrast to bark beetles, which feed in the more nutritious sapwood. Notes on the biology and distribution of five species of Xyleborus are given here. Many new invasive species within this group have been detected recently in North America. One invasive species, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff), is discussed in a separate page.

Hosts Commonly Attacked

Natural enemies of these beetles are poorly known.

Biological Control Agents

Natural enemies of these beetles are poorly known.


Atkinson, T. H., R. J. Rabaglia, and D. E. Bright. 1990. Newly detected exotic species of Xyleborus (Scolytidae) in eastern North America, with a revised key to species. The Canadian Entomologist 122: 93-104.
Haack, R. A. 2006. Exotic bark- and wood-boring Coleoptera in the United States: recent establishments and interceptions. Canadian Journal of Forest Research 36 (2): 269-288.