Pest

Bark beetles of pine and spruce

Dendroctonus and Ips spp. (mountain pine beetle, pine engraver, spruce beetle)

Small, dark beetles that bore through the bark in large numbers and carry blue-stain fungi that block the wood. They kill drought-stressed, crowded or old trees first. The needles turn 8 to 10 months after attack, about when the next brood flies.

Signs

• Pitch tubes: popcorn-like blobs of resin, pink, brown or white, on the trunk.
• Reddish boring dust in bark crevices and around the base.
• The whole crown turning yellow to red 8 to 10 months after attack; vertical egg galleries under the bark.

What favors it

Drought, crowded stands, and old or large-diameter pines.

Prevention

• Water high-value pines and spruces in dry spells; drought-stressed trees are attacked first.
• Thin crowded stands so the trees left have room and water.
• Pile and burn or chip fresh pine slash before beetles fly in May.

Crops it shows up on

Evergreens & conifers (pine, spruce, juniper).

Often confused with

Sources

• Mountain Pine BeetleMontana State University Extension
• Engraver BeetlesMontana State University Extension
• Mountain Pine BeetleColorado State University Extension

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