INSECT ENEMIES OF WESTERN FORESTS 



95 



colonies, without forming tents, on alder, birch, poplars, willows, 

 and a large number of broadleaved trees. These caterpillars are 

 distributed generally over the United States. 



The eastern tent caterpillar (Malacosoma americana (F.)) has 

 a white line on the back, bordered with reddish brown, and on the 

 sides a row of blue spots and reddish-brown and yellow lines. It 

 feeds on various fruit, shade, and forest trees in the Eastern 

 States and is found in the Rocky Mountain region from New 

 Mexico to British Columbia. 



The California tent caterpillar (Malacosoma calif ornica Pack.) 

 is orange red to brown above and paler brown below, with a blue 

 line on each side. This species is found in California, where it feeds 

 on ash, madrone, oak, willow, and other forest, shade, and fruit 

 trees. 



The blue-sided tent caterpillar (Malacosoma constricta Stretch) 

 has an orange-brown body, with distinctly blue sides and blue dots 

 along each side of the center. It feeds on oak and other trees in 

 Arizona, California, and Oregon. 



The Great Basin tent caterpillar (Malacosoma fragilis Stretch) 

 (fig. 37) is distributed in the Great Basin region between the 





Figure 37. — The Great Basin tent caterpillar (Malacosoma fragilis) 

 Adults; B, larva; C, pupa; D, cocoon. Natural size. 



Rocky Mountains and the Cascade-Sierra Nevada ranges, where it 

 feeds on bitterbrush, aspen, oak, poplar, willow, and other shrubs 

 and trees. The caterpillars of this species are distinguished by 

 having a pale-blue head and a brown-to-black body, with a broad, 

 pale-blue stripe down the middle, fine orange lines on each side of 

 the center, and two blue spots on the sides of each segment. The 

 hairs are whitish. 



The western tent caterpillar (Malacosoma pluvialis Dyar) (fig. 



