Species Xyleborinus saxesenii - Fruit-tree Pinhole Borer

Common Eurasian Ambrosia Beetle, Asian Ambrosia Beetle; Lesser Shot Hole Borer(1)

Xyleborinus saxesenii (Ratzeburg 1837)

From (2): “Wood and Bright (1992) (3) and most authors list this species as X. saxeseni, but Holzschuh (1994)(4) points out that Ratzeburg's original description was saxesenii, with the ii ending.”

2.0-2.4 mm (2)

Native to, and widespread in, the Palaearctic(5), adventive in NA, with disjunct populations in the east (NS-FL to ON-KS-TX) and west (BC-CA)(6)(7)

Wide host range that includes ornamental trees, stone fruits and timber. Almost all conifers and hardwoods are susceptible. Economic damage to fruit trees has been particularly devastating.

This species feeds only in dying trees and generally trunks of large size. Oak, hickory, beech, and maple seem to be preferred. Much injury is done to timber because the flat chambers cannot be remedied by plugging.(8)

The young are gathered in a brood chambler at the end of a gallery into heartwood. They are standing on edge, parallel with the grain with little only the thickness of the body as the space between the gallery walls. The entire wall surface of the gallery is plastered with ambrosia fungus. The brood chamber can be packed with eggs, larvae, pupae, and adults. The larvae extend the chamber, wood passing thru their bodies becoming mustard-yellow. Most of this is ejected from the colonies but a portion is retained to form a bed for new crops of food fungus.(8)

The life cycle is short and can be completed in 2 months.(9)

earliest record in our area: CA 1911(10)

Bark and Ambrosia Beetles(6)

Fact sheet - Espinosa & Hodges (2009)