boring insects

[D. Dexter]

I am interested in any info on boring insects that attack Pseudotsuga 
menziesii and Tsuga heterophylla in the Pacific Northwest (western Washington, USA).  
They seem to bore holes mainly in dead and dying trees but resently have been 
attacking seamingly healthy trees. In particular I would like info on 
species, lifecycles, and measures that can be taken to protect trees.
                                               Thank you,
                                               Dennis Dexter