Newcomers to the Phoenix area are sometimes horrified when they get their first glimpse of a huge bug that, for some, resembles a monstrous cockroach. Yes, this adult bug can be up to six inches long. Even worse -- it flies.
It is the Palo Verde Beetle. More specifically, the Palo Verde Root Borer (Derobrachus geminatus). They have long antennae and spiny collars. They come out each July, and are most active in the early evening. The young Palo Verde bugs fed on the roots of distressed trees and shrubs, particularly the Mexican Palo Verde tree. After a few years, they leave the tree roots. You'll be able to see the exit holes around the roots of the tree. It does no good to spray inside the holes after the Palo Verde beetles have already left.