INSECT ENEMIES OF EASTERN FORESTS 481 
the folage overlapping one another like the scales of a fish. The 
mature larva is about 1 inch in length, tapering shghtly from the 
middle to the end. It is dark brown or dark reddish brown with 
conspicuous, whitish-yellow, piliferous tubercles. The head is shin- 
ing black and the thoracic shield brownish. The pupa is about 5% 
inch in length and is of a pale brownish yellow, later changing to dark 
reddish brown (Swaine, Craighead, and Bailey, 403). 
This species is distributed throughout practically the entire range 
of its food plants and is one of the most destructive forest insects mm 
North America. There are apparently a number of biological vari- 
FIGURE 112.—The spruce budworm (Archips fumiferana) : A, Eggs on under side 
of fir needle; B, half-grown larva; C, full-grown larvae; D, pupae; LH, fir twig 
with pupa attached; F, defoliated fir twig with empty pupal cases; G, adults. 
eties, or races, that are distinct in their food habits, the food plants 
including alpine, balsam, and lowland firs, Douglas-fir, black, red, and 
white spruces, Scotch, jack, red, ponderosa, and lodgepole pines, hem- 
lock, larch, and probably other conifers. The greatest economic dam- 
age has been caused to spruce and balsam fir in southeastern Canada, 
Maine, and northern Minnesota. In the Lake States a biological race 
that prefers Scotch pine and jack pine was studied by Graham (192) 
In the West, Douglas-fir and true firs are the preferred hosts in some 
localities and lodgepole pine in others. Recently serious defoliation 
of ponderosa pine has occurred in Colorado. 
In the Northeast, the moths are active late in June and in July, and 
in the Lake States during July and early August. The eggs hatch 
within 8 to 12 days, and the young larvae cr awl about until they find 
suitable places, often under bark scales, to spin their small hiber- 
