INSECT ENEMIES OF WESTERN FORESTS 79 
The spruce budworm (Harmologa fumiferana Clem.) (25, 82) 
(fig. 88) is one of the most destructive members of this group. In 
the Northeast, in Canada, the Lake States, and the northern Rocky 
Mountain region it has caused widespread destruction of spruce, 
balsam firs, and Douglas fir. There are many records of budworm 
epidemics in the Northeast in which enormous numbers of spruces 
and balsams have been destroyed. It was not until 1922, however, 
when two outbreaks were recorded in widely separated sections of 
FIGURE 38.—The spruce budworm (Harmologa fumiferana) : A, Eggs on under side of fir 
needle; B, half-grown caterpillar; C, full-grown caterpillars; D, pupae; H, fir twig 
with pupa attached; F, defoliated fir twig with empty pupal cases; G, adult moths. 
All natural size. (Hvenden.) 
Idaho, that it was recognized as an important enemy in western 
forests. The following season it was found that a budworm epi- 
demic had been present for several years in the southwestern corner 
of Yellowstone National Park and the adjacent Targhee National 
Forest, and in the next few seasons outbreaks were reported from 
many Western States. In some areas these outbreaks reached alarm- 
ing proportions and heavy timber losses followed. Though it is not 
known whether this insect migrated or spread to the western part 
of the United States from infested areas in the East, it is believed 
that it is indigenous to the West and that during the last 30 or 40 
years it has been at such a low endemic stage as to escape attention. 
The adult spruce budworms are-small, mottled, brownish moths 
with a wing expanse of approximately 1 inch, with no distinctive 
markings, the general color tone being a dull gray. The oval, scale- 
like eggs, which are light green and about one-sixteenth of an inch 
in diameter, are laid on the under side of needles, in an overlapping 
form like shingles, with about one-third of the egg exposed, The 
eee 
RS 
rs 
- 
863 ee Eee Lt. 
Ok" © pS | aati 
.* a oo - 
