a wide variety of hardwoods. In the North and West, trembling 
aspen is preferred; in the South, tupelo gum, black gum, sweet 
gum and various species of oak are most heavily defoliated. The 
adult is stout-bodied, light buff-brown, and has a wingspread of 
about 25 to 37 mm. The forewings have two darker oblique bands 
near the middle (fig. 127A). Full-grown larvae have light blue 
heads mottled with black and sparsely covered with fine, whitish 
setae. Each abdominal segment is marked dorsally with a yel- 
lowish-buff, keyhole-shaped spot which may be divided to form an 
anterior spot and a smaller posterior spot (fig. 127B). The venter 
is blue-gray to dark gray, usually with a median spot on each 
segment, and often with a dark-gray area running full length of 
the body between the bases of the legs. 
Winter is spent in the egg shape and hatching occurs in the 
spring, about the time the buds on the host tree begin to swell. 
Young larvae feed on expanding buds; older ones devour the 
foliage, often completely defoliating the tree. During the first 
three instars, the larvae are gregarious. At first, all of those from 
A AND B COURTESY OF CONN. 
AGR. EXPT. STA.. C, F-506692 
grown caterpillar, showing 
FIGURE 127.—Forest tent 
caterpillar, Malacosoma 
disstria: A, adults; B, full- 
grown caterpillar, showing 
key-hole spots along the 
dorsum; C, caterpillars at 
rest on trunk and branches 
of an aspen. 
