Science & Environment

Wildfires, drought create ripe conditions for bark beetle outbreaks

By April Ehrlich (Jefferson Public Radio)
May 6, 2021 9:47 p.m.
A stand of trees on a hill shows some with brown, dead needles.

Ponderosa pines show dieback caused by Ips bark beetles, which attack a wide variety of pines injured by fire or storms or weakened by drought.

Oregon Department Of Forestry

Last year’s Labor Day fires have created ripe conditions for infestations of tree-killing bark beetles.


Bark beetles normally target trees that are struggling to stay alive. Two beetle species are native to Oregon and often help keep its forests healthy by taking out weak or dying trees.


But severe drought and last year’s intense wildfires means more parts of the state will become infested.

“We will have some localized areas where we will have some outbreaks and an uptick in populations,” says Christine Buhl, an entomologist with the Oregon Department of Forestry. “That could spill over and overwhelm the defenses of not just the struggling trees but then some adjacent healthy trees.”

Bark beetles normally lay their eggs under tree bark. After they hatch, they feed on the tree’s tissues that are needed to move water and nutrients from its roots.

Beetle bark outbreaks normally subside within a couple of years. Landowners can remove some beetle-infested trees to reduce the risk of a larger outbreak. They can also consult with a specialist from ODF or the Oregon State University forestry extension.

Buhl says ongoing drought means the state will likely continue seeing large beetle infestations in future seasons.

“Statewide, we’ve been enduring hot droughts for multiple years,” Buhl says. “And that is the primary stressor we need to focus on is planning for climate change and ongoing hot droughts, because that’s going to yield the most resilience against these trees against bark beetles and future risks.”


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