WSU Extension


Caption: Bark beetle larval galleries
Photo by: A.L. Antonelli
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Pine : Mountain pine beetle
(revision date: 3/10/2017)

The mountain pine beetle attacks pine trees (trunks and branches) four or five inches in diameter or larger. The adults and larvae mine the bark, weakening and girdling trees. Heavily infested trees may decline or die. Red sawdust on the bark and ground and pitching on the trunk or large branches may indicate the presence of these bark beetles. Adults are black and about 1/4" long. Larvae are white and found under the bark in straight galleries. Bark beetles typically attack weakened trees. Lodgepole pine is the preferred host, but other pines are also attacked.
Management Options

Non-Chemical Management
  • Provide proper culture for trees. Healthy, vigorous trees are much more resistant to beetle attacks.
  • Remove severely infested trees to prevent possible infestation of nearby trees.
Select non-chemical management options as your first choice!

Chemical Management

Make applications in early June or prior to beetle flight. Apply from ground level to limbs 5 inches or more in diameter. This is a preventive treatment spray and will not control or kill beetles once they have entered the tree. Sevin (carbaryl) is particularly dangerous to honeybees since it does not immediately kill them. They return to the hive with the poison and distribute it within. Therefore avoid carbaryl if any possibility of spray drifting onto nearby blooming plants. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • GardenTech Sevin Conc Bug Killer
    Active ingredient: carbaryl  |  EPA reg no: 264-334-71004
  • This list may not include all products registered for this use.
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Caption: Bark beetle larval galleries
Photo by: A.L. Antonelli
Caption: Bark beetle (very similar to shothole borer)
Photo by: A.L. Antonelli