tent, but on the leaves of neighboring branches. As they crawl 
to these branches, they spin strands of silk which they usually 
follow in returning to the tent, where they remain during periods 
between feedings. Species that do not construct tents assemble 
in clusters on branches and trunks during periods between feed- 
ings. Toward the end of an instar they spin nests of silk on 
branches and trunks on which they congregate to molt. 
The larvae usually pass through five or six instars. By the time 
the last instar is reached, they are no longer gregarious, and 
they travel extensively in search of food. At this time, they are 
not very selective in their food requirements and will feed on a 
wide variety of hosts. When their food supply becomes scarce, 
they may migrate in search of other food, often for considerable 
distances. When they reach maturity, they spin cocoons in which 
to pupate. The cocoons are about 1-inch long, fairly loosely con- 
structed, and white or yellow because of a powdery material dis- 
persed between strands of silk. Cocoons may be found within 
the old tents, inside logs, beneath loose bark, and between folded 
leaves. 
The eastern tent caterpillar, Malacosoma americanum (F.) (fig. 
126), is generally distributed throughout the eastern half of the 
United States and southern Canada. Its preferred hosts are wild 
cherry and apple, but it also attacks a wide variety of other 
forest, shade, and fruit trees. The adults are light to dark choco- 
late-brown, the wings are lightly dusted with white scales, and 
the wingspread varies from about 37 to 50 mm. Each forewing 
is crossed by two oblique white or yellowish-white lines. The 
hindwing is uniformly chocolate-brown and crossed by a faint 
white area. Full-grown larvae have black heads, sparsely clothed 
with long, fine, light-brown hairs, and are marked with an appar- 
ently continuous mid-dorsal light stripe, bordered on each side 
with longitudinal reddish-brown and black wavy lines. The sub- 
dorsal area is marked with a central black area on each segment, 
crossed by a vertical blue mark posteriorally. 
Winter is spent in the egg stage, and hatching occurs about the 
time the buds of the host tree begin to unfold in the spring. In 
Florida, adults may appear and lay their eggs even before hatch- 
ing occurs in the northern parts of the insect’s range. The larvae 
are gregarious. As soon as they hatch, they begin the construction 
of a tent in a nearby crotch, and continue to enlarge it as they 
grow. From this tent, the larvae craw! out to the foliage to feed. 
After feeding, they return to the tent to rest. When they become 
full-grown, they leave the nest and wander in search of places 
to pupate. Pupation occurs in tough silken cocoons, dusted with a 
yellowish powder, on the bark of trees, on fences, on brush and 
weeds, among dead leaves and other debris on the ground, and | 
even on the sides of buildings. When the adults appear, they lay | 
eggs in essentially a clasping mass on small twigs or branches, t 
or on the trunks of small trees. In the Lake States, eggs are often | 
found on the trunks of very small trees about 6 inches above the 
ground. There is one generation per year (102, 600). : 
Most of the hosts of the eastern tent caterpillar have little | 
value, thus it usually does not cause economic losses. It may be | 
of some importance, however, when it defoliates commercial size | 
328 
