An estimated 10 million trees were killed during this outbreak. Approximately five outbreaks have occurred since that time though none has reached the same magnitude. The outbreak in the early 1970s resulted in the loss of more than 440,000 trees. The last outbreak occurred from 1988 to 1992 and resulted in the death of approximately 50,000 trees. Beetle populations appear to be increasing in 1999 and another outbreak is expected during the next five years.
Severe outbreaks can increase fire hazard as well as stream flow.
The snags, however, are also beneficial as habitat for cavity-nesters. The summer that a tree is attacked it will appear green and healthy. The first signs of the attack will be noticeable by late summer. There will also be red boring dust in bark crevices and on the ground around the tree. These trees can be identified by larger pitch tubes with the adult beetle often stuck in the resin.