Boise National Forest experiences damaging Tussock moth outbreak

BOISE, Idaho (CBS 2) — The Boise National Forest is experiencing another outbreak of Douglas-fir Tussock moths/caterpillars, which damage trees and can be harmful to some individuals.

The U.S. Forest Service wants to remind forest visitors not to touch or pick them up.

The moth’s tree-damaging caterpillar has long bristly hairs that may cause allergic-like reactions for some individuals.

A rash called tussockosis can persist from a few hours to several weeks.

Individuals do not have to come in contact with the caterpillar to be effected as the hairs may be airborne," said the U.S. Forest Service - Boise National Forest. "Reactions can worsen with exposure and can compromise airways for some individuals."

Tussock moth population began to increase in 2016 following with outbreaks typically lasting 3-4 years and subside when natural enemies such as a virus-specific to the caterpillars and non-stinging parasitic wasps that kill the caterpillars.

This year is expected to be the last year of the outbreak and caterpillar populations should crash by the end of August.

Defoliation is now visible and looks like reddish half-chewed needles and tends to be worse in the tops of trees.

While the trees may look dead because the caterpillars feed on the needles, they are not, and should not be cut for fuelwood. If trees have any green needles, don't cut them.

Options for control are somewhat limited over a large area. Dense stands of trees are impacted more severely than more pend stands.

Dry sites, ridges, and dense stands tend to have more damage because trees have less water to recover from feeding damage. For more information:

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