General Information
Adult Western pine beetles are dark brown and about ¼ inch long. Larvae are small, white, legless grubs. Western pine beetle larvae mine a short gallery in the phloem and then turn into the middle bark to complete their development. Attacking beetles release chemicals called aggregating pheromones that attract other beetles until a mass attack overcomes the tree. Attacks may “spill over” into adjacent trees causing what is known as a “group kill.”
Western pine beetles typically fly from late spring through late October. One to three generations may occur in a single year. The adult gallery pattern of the western pine beetle is winding and crisscrosses in several directions. It is the only bark beetle that makes this particular type of gallery.
When did this start?
This catastrophic event actually started in 2014. Due to many factors including overcrowded stands of trees, short warm winters, and low precipitation. During those winters the beetles were able to experience a rapid buildup in numbers which probably exceeded one trillion insets.
What is going to stop this major infestation?
Due to many factors only natural systems will stop this infestation. Wet years, less trees and long cold winters are what is needed to slow and stop this infestation. This type of infestation has occurred several times in the last 30 years and natural systems stopped those past infestations.
Has this extreme die off happened before?
It is possible that it could have occurred in the past. It is less likely though as healthy forests over the past thousands of years were able to resist both fire and pine bark beetles.
How many beetles does it take to kill a tree?
Theoretically, just a few beetles could kill a tree. However, conditions would have to be perfect for this to happen. As can be seen in this photo hundreds of beetles attacked this tree which is how the beetles normally infest a tree. They usually attack in swarms and over whelm the tree.
Are beetles native to this area?
The Pine Bark Beetle has been around as long as the trees themselves. The beetles are actually a very necessary component to a healthy forest.
What animals prey on the bark beetles?
Woodpeckers are the primary predators of bark beetles. Woodpeckers can be seen pecking at infested trees and eating the beetles when they are in the larva stage.