There's a new insect pest in Southern California, the Polyphagous Shot Hole Borer (PSHB). This small ambrosia beetle spreads a fungal pest, and together they can kill trees in urban, suburban, and natural landscapes. The beetle has been found on over 200 species of tree, but there are 19 that have so far been found to host both the beetle and the fungus - these are known as reproductive hosts. These include California natives like Coast Live Oak and Sycamore, as well as common street trees like Box Elder, and a tree found in backyards and commercial orchards,   Avocado. The PSHB joins the Goldspotted Oak Borer in threatening our native trees. When insect pests kill trees, they increase the fire risk by increasing the dead fuels available. To find out more about these pests, visit our new web site, Pests and Diseases of Southern California Oaks.