Foliage

Hosts-- Primarily ponderosa, Jeffrey and lodgepole pines.

Distribution-- In Utah, California and Wyoming, primarily where hosts are growing on pumice or decomposed granite soils which allow larvae to bury themselves in soil for pupation.

Damage-- This insect is rarely seen except in outbreaks, which occur at 20-30 year intervals. During outbreaks, which can last several years, growth loss and mortality can be significant. Pandora moth has a two-year life cycle so most of the defoliation occurs every other year. Terminal buds are not damaged so even severely defoliated trees usually recover, although heavy defoliation can predispose trees to attack by bark beetles.

Identification-- First instar larvae are brown, covered with dark hairs and have a black head. They feed in clusters around needles on the outer branches. Late instar larvae are about 3 inches long, brown to greenish -yellow with a few branched spines at each segment (fig. 216). Large green droppings and molted skins from larvae may be conspicuous on the ground under heavy populations. The large, dark purplish-brown pupae are found in the soil beneath the pines (fig. 217).

The moths are large, with wingspans of up to 4.5 inches. They are heavy-bodied, grayish-brown with a dark spot near the center of each wing. Males have feathery antennae while those of females are narrow (fig.218). During epidemics, thousands of these moths can be seen flying in the forest canopy.

Similar damages-- Defoliation by pine butterfly and sawflies.

References-- 7, 22, 50, 58

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A Field Guide to Diseases & Insect Pests of Northern & Central Rocky Mountain Conifers