Ips - first recognized sign of attack is yellowing or reddening of needles in tree crowns. Generally, by the time this is seen the beetle has completed its development and moved on to other trees. The male attacks the tree first and constructs mating chambers. After mating the female lays the eggs small galleries radiating out from the chamber. This boring grooves the surface of the sapwood, parallel with the grain.
Ips beetles introduce blue stain fungus into egg galleries.
The larvae feed on the fungus, and it is the fungus that will block water flow and ultimately cause the death of the tree. At the point of attack, the tree usually exudes a resin pitch tube about the size of a small piece of popped popcorn. The initial site of attack is usually at midtrunk or in the lower crown, but they will attack from the base to the crown. They introduce the blue stain fungus that once established is deadly to the tree. The larvae bore small channels off the galleries.