Identifying Symptoms

Symptoms of Mountain Pine Beetle Infestation

Check the Needles

In mountain pine beetle-infested trees, needles start to fade and eventually become rust colored. Fading, which starts in the lower crown and moves upward, generally appears eight to 10 months after the attack.

Standing dead pine trees killed by Mountain Pine Beetle.

Pitch Tubes

Look for pitch tubes on the lower 15 feet of the tree trunk. These tubes appear as cream or pinkish colored masses resembling popcorn.

Pitchtube caused by Mountain pine Beetle on bark of pine tree.

Blue Staining

Use a hatchet to peel back the bark to check the sapwood for blue staining caused by the fungus.


You may also notice frass (sawdust-looking material) in the cracks of the bark or at the base of the tree.

Woodpecker Feeding Holes

Woodpeckers may feed on the MPB larva found underneath the bark. Look for feeding holes one-half to three-quarters of an inch wide along the trunk, along with bark flakes at the base of the tree.

Woodpecker on trunk of pine tree.