64 MISC, PUBLICATION 273, U. S. DEPT. OF AGRICULTURE 
beneficial insect, and during the following season it was practically 
impossible to find a living caterpillar or butterfly within the de- 
fohated areas. Before natural control becomes effective, however, 
tremendous loss of timber may occur. 
In the future, artificial control by airplane dusting may prove 
useful in protecting the forests from heavy defoliation during the 
peak of the outbreak and until the defoliator is brought under 
control by natural means. Even if only 50 percent of the foliage 
ot a tree could be saved by such a method it probably would be 
sufficient to prevent its death. 
The Pandora moth (Coloradia pandora Blake) (68) (fig. 29) is 
an important defoliator of ponderosa pine in the forests of central 
and southern Oregon and in California east of the Sierra Nevada. 
This moth and closely related species and varieties have been re- 
ported from practically all Western States, where they feed upon 
various pines. The preferred hosts of the pandora moth are pon- 
derosa and Jeffrey pines, though lodgepole pine may also be attacked 
during epidemics when in mixture with one of the preferred species. 
Though distributed over a wide area, it is only in pine forests grow- 
ing on loose pumice soil, where thé caterpillars can easily bury 
themselves for pupation, that serious damage has occurred. 
The most recent destructive outbreak occurred on the Klamath 
Indian Reservation of southern Oregon from 1918 to 1925. Thou- 
sands of acres of ponderosa pine forest were heavily defoliated, with 
an accompanying serious loss of timber. Heavily defoliated trees 
were unable to recover and died after 2 or 3 years as a direct result 
of the injury. Others were greatly reduced in growth and re- 
covered only after a period of several years. The loss in growth 
throughout the defolated area amounted to several million board 
feet. Even more serious was the bark-beetle damage which fol- 
lowed the defoliation and increased to alarming proportions in the 
weakened trees. 
While some infestation may be found every few years, the records 
indicate that epidemics occur at fairly regular intervals of 20 to 
380 years and continue in intensity for from 6 to 8 years. During 
periods of abundance fairly heavy feeding may occur without serious 
consequences. This is due to the fact that the terminal buds are 
not eaten, and since the insect has a 2-year life cycle and the larvae 
feed only in alternate years, the trees have an opportunity to re- 
cover. For this reason the more vigorous trees survive the attacks, 
and only during the major outbreaks are heavy losses likely to 
be sustained, 
The adults are large, heavy-bodied, grayish-brown moths with a 
wing expanse of 3 or 4 inches, and a small dark spot near the center 
of each wing. The base and interior margins of the hind wings are 
clothed with pinkish hairs, which in the male shade to wine color. 
The males have large, feathery antennae, while the females have 
slender antennae and heavy bodies, During epidemics thousands 
of these large moths will be seen fluttering over the tree trunks 
and flying through the woods. The eggs, which are globular in 
shape and about one-tenth of an inch in length, are laid in clusters 
on the trunks or branches of trees or on litter on the ground. The 
