This question comes from a homeowner in Washington state.
Based on a study performed by the International Research Group on Wood Preserveation, ACQ is effective in protecting wood against the Powderpost beetle.
Michael Merchant, Ph.D., Professor and Extension Urban Entomologist, with Texas AgriLife Extension Service states, "The most commonly infested woods include ash, oak, hickory and walnut." He also explains in an article on the Texas A& M website, that powderpost beetles pose little threat to the structural integrity of most homes because they are framed with softwood lumber, and thus not susceptible to attack. Removing infested wood and replacing it with treated wood will eliminate the problem in most cases.
Aaron Sooter, Technical Services Representative