Pest description and damage The adult is a large, brown-gray, heavy-bodied moth with black markings on the wings. Pandora moth larvae are brownish- to yellowish-green, spiny, and about 1 inch long at maturity. The larvae feed on the needles of pines, especially ponderosa, Jeffrey, and lodgepole. The stubs of eaten needles remain on the twigs, and the crowns of infested trees often are thinned. The larvae may cause severe defoliation when there are large outbreaks. They travel in single file when moving to new feeding areas. This is a sporadic pest of forest and landscape trees.
Biology and life history The adult moths emerge in midsummer and lay eggs on pine needles or bark. The larvae emerge and feed on new foliage throughout the summer. They overwinter on the tree in clusters then resume feeding in spring. They drop to the soil to pupate. Pupation lasts for at least 1 year. Control is not needed except in outbreak years.
Pest monitoring Be alert for signs that the population is growing: increased defoliation or clusters of larvae in the winter.
Prune out severely defoliated sections of the tree. Pick larvae by hand if found. These larvae are considered a delicacy among the tribes in areas where they are found.
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