Polyphagous Shot Hole Borer

Things That Go Crunch In The Bark

By Frank Landis, Chairperson Conservation Committee 

There's something about reading about Polyphagous Shot Hole Borers and commenting on the North County Multiple Species Conservation Program (MSCP) that just inspire me.  Sadly, I'm not sure anyone will appreciate what I'm thinking about.

Probably most of you are aware of the Shot Hole Borers (http://ucanr.edu/sites/pshb/ is the easiest source of information).  There are two species that are physically indistinguishable, but which are genetically distinct and come from different parts of Asia.  In San Diego County, we have the Kuroshio Shot Hole Borer (Euwallacea sp. I'm still looking for the specific epithet.  Let's call it KSHB), and it also has been found in Orange County and Santa Barbara as well.  Up in LA and Ventura, they have the Polyphagous Shot Hole Borer (also Euwallacea sp.  I'm still looking for the specific epithet, and I don't think it has one either. We'll dub it PSHB). 

The problem with these two non-native beetle species is that they like to burrow into the trunks of trees, and like other ambrosia beetles, these tiny pests –they're about the size of a comma or a period on paper—bring their own species of fungi with them (Fusarium euwallaceae and a Graphium species).  These fungi, along with the beetle galleries in the trunk, kill the trees.