Trees damaged by beetles
Mountain pine beetle damage to a forest in British Columbia. (Photo credit: UBC Micrometeorology / Flickr)

It’s a good time to be a bug and a bad time to be a tree.

That’s according to Jeff Hicke of the University of Idaho. Based on aerial surveys, he estimates that since 1997, bark beetles have killed more than 5% of the forested area in the western United States.

And global warming is likely to make the problem worse.

Hicke says that droughts in the northwest can leave trees stressed and more vulnerable to attack. Meanwhile, rising temperatures can make the beetles more numerous.

“For mountain pine beetle, which is the most damaging of the bark beetle species in western North America, we expect warming to reduce beetle mortality during wintertime,” Hicke says.

Warming also speeds up the development of insects so that more generations of the beetles can be born each year. And like something out of a horror movie, when more beetles emerge at the same time, they can mount mass attacks that overwhelm a tree’s natural defenses.

“Temperature will allow populations to synchronize within a stand, emerge, and move to the next tree to attack it more successfully,” Hicke says.

So climate change could lead to even more bark beetle outbreaks in already-stressed western forests.

Reporting credit: ChavoBart Digital Media.