Polyphagous Shot Hole Borer

PSHB_a_IMAGE PSHB_B._-Syc8 PSHB_c_image_Dead_Syc2 PSHB_D_imagePolyphagous Shot Hole Borer (PSHB) is an exotic ambrosia beetle that was first detected in 2003 in Southern California and was recently found to be killing or infesting several hundred species of trees. It is currently found in L.A., Orange, San Bernardino, western Riverside, and San Diego Counties.
The “ambrosia” name refers to a symbiotic fungus that is carried by the female in special organs in her mouth parts. The fungus is grown in the beetle galleries and both the adult beetles and larvae feed on the fungi. The adult beetles are very small, ranging from 0.05 to 0.1 inches in length. They come in a range of shades between black (females) and brown (males) coloring. While this beetle attacks a large number of plant species, the majority of which are hardwoods, it can only reproduce in 31 species including maples, sycamore, oaks, willows, alders, and avocado.


The characteristics of PSHB attack and fungus infection differ among tree species. The beetle commonly attacks the main stem and larger branches of trees and shrubs, but injury can be found on twigs as small as 1 inch in diameter. The beetle produces a very precise, perfectly round, tiny (< 0.1 inches in diameter) entry hole in most trees. Wet staining and discoloration on the bark of the main stem and branches are early symptoms of beetle attack. Depending on the tree species attacked, PSHB injury can be identified either by staining, gumming, or a sugaring response on the outer bark. Infection with the fungus can cause leaf discoloration and wilting, dieback of entire branches, and tree mortality.

Info Source: Arborjet

Trees will recover from infestation and will be protected from Polyphagous Shot Hole Borer after the effective treatment that Joe’s Tree Care offers. We have certified arborists that can help you keep your trees health! Call us today! 512-215-1551