WSU Puts the Dangerous Western Pine Beetle In Focus

WSU Extension is offering education about the western pine beetle at its upcoming Forest Owners' School session in Spokane.

The western pine beetle is killing trees

In a 2023 report, the Washington Department of Natural Resources (DNR) and U.S. Forest Service reported that over half of tree mortality was due to predatory bark beetles. The ponderosa pine's mortality due to western pine beetle was marked at a 16-year high of 44,300 acres.

The increase in beetle activity is likely due to drought conditions and extreme heat events. The stress placed on tree, and beetle, leads to increased chances that the pines can't fight off the beetle. In the end, dead trees remain - a perfect source of tinder for wildfires.

The beetle is still an important part of the ecosystem

Despite the harm it can do to the ponderosa pine, the western pine beetle remains an important guest in the forest. Their activities help cull weaker trees, ensuring the forest grows strong.

The beetle is small but inflicts an impressive amount of damage. Female beetles bore past the outer bark of a tree, and then weave through the wood toward the tree's phloem, which is full of nutrients. But the pine isn't defenseless.

Washington State University Extension Forester Andy Perleberg explains:

When I work with forest owners, I explain that tree competition, weather, climate, disease, and, for eastern Washington especially, availability of water all influence the health of the ponderosa pine. Once a tree is stressed from damage or water deficiency, pine beetles can gain a foothold and finish them off.

Pines have a number of resin ducts within the phloem - drilling into these releases a special pitch that halts the beetle, almost like a sudden pour of cement.

“If you see globs of pitch on the outside of a tree that are yellow or cream colored, that means the tree won,” said Perleberg.

WSU is offering pine beetle education at upcoming Forestry School

Perleberg will be presenting education on the western pine beetle at the upcoming Forest Owners' Winter School. He explains:

I educate forest landowners on the relationship between tree diameter and insect and disease resistance. Trees portion out their energy, first to root growth, then into upward growth to increase their height, then into diameter growth to support a big root system and a heavier top. It’s when we start to see increases in diameter that the tree is most resistant to pests and diseases.

The pine beetle will be one of many topics covered in the day long session, which includes almost 20 courses focusing on forestry and timber.

If you are unable to attend, consider reviewing available online resources including:

• Oregon Department of Forestry: Western Pine Beetle Fact Sheet
• USDA Fact Sheet
• US Forest Service Fact Sheet