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Signs of Green Attack

Pitch tubes or pitch-outs:
Pitch tubes are one way to recognize green attack trees. Host trees produce pitch tubes to defend themselves against bark beetles. Healthy trees have a more vigorous resin production, enabling them to better “pitch out” the beetles. One of the best ways to keep your trees healthy and able to defend themselves is to water adequately, especially during drought conditions. You can tell if a tree is still healthy by using a hatchet to make a nick in the bark through the wood. If the inner bark is white and pulpy, the tree has won and will probably survive. If it is brown, the tree is likely infested and will die. Remove more bark to confirm this.

Frass:
Another symptom of green attack is frass—a mostly sawdust-like substance from the beetles building galleries. Frass can be found in the crooks of branches, in the bark crevices, at the base of the tree, and in cobwebs in late summer.

Fading Foliage:
A final sign of green attack is fading foliage—starting mostly at the tops of the tree. Ponderosa pines tend to fade late in the year that they were attacked. Unless the summer is unusually hot, Lodgepole pines usually won’t fade until the summer following an attack.