2010-10-24

Bark beetles threat waning?

As the effort to remove beetle-killed trees along forest roads gets under way this week, it appears that the number of mountain pine beetles in trees on the Helena and Beaverhead/Deerlodge national forests is declining, which could signal that the epidemic has peaked here.

Greg DeNitto, the group leader for forest health protection at the regional national forest office in Missoula, said a survey of trees on the two forests during the summer showed fairly high beetle mortality. Forest Service experts theorize that three circumstances may have impacted the rice-size bugs, which kill pines by drilling under the bark in the summer and eating their way around the tree during the winter, interrupting the flow of nutrients.

“Especially around Helena and Butte, that outbreak has been going on for a number of years, and essentially they’re running out of food, so the population is declining,” DeNitto said on Monday. “We don’t have a lot of information or data, but we also suspect that an early cold snap last October, and then the cool, wet summer, also contributed to the decline, or at least had some effect on the population by disrupting the beetle’s normal progress.”