INSECT ENEMIES OF EASTERN FORESTS 439 
The moths emerge in September and October. Mating takes place 
without the female leaving her bag, and then the eggs are deposited 
in the pupal case. The winter is passed in the egg stage. Hatching 
takes place in late spring, and the larvae crawl to the nearest foliage 
and immediately begin to construct their cases. Large quantities of 
silk are spun and the case or bag is enlarged as the larva grows, so 
that 1t may conceal itself within at any time (fig. 92, D). The young 
larva first feeds on the epidermis of the leaf, and later eats all but the 
larger veins. It becomes full grown, attaches its bag with silk to a 
twig, and pupates within, in August or September. On deciduous 
trees the bagworm can be controlled by hand picking the bags in 
winter, but on evergreens this method is impractical, and spraying the 
foliage with lead arsenate (p. 53) when the larvae are feeding is the 
most efficient method of control. For caution in the use of ar- 
senicals see p. 34. 
Figure 92.—The bagworm (Thyridopteryx ephemeraeformis): A, Full-grown 
larva; B, female pupa; C, adult male; D, characteristic cases, or bags. 
Famity LIMACODIDAE 
The Slug Caterpillars 
The moths of the Limacodidae are medium to small, vary greatly 
In appearance, and many are delicately colored. ‘The bodies are stout, 
and the vestiture often long and woolly. The larvae are sluglike and 
the large head is concealed in the thorax. The thoracic legs are small 
and the prolegs replaced by sucking disks. The larvae are of various 
forms, one group smooth and another with spines. The prepupal 
larva hibernates in its oval or nearly spherical cocoon, which is of 
densely woven silk spun between leaves or attached to a twig. The 
moth pushes off a lid at one end of the cocoon when ready to emerge. 
Representatives of this family occur throughout the United States. 
They are rather general feeders on foliage of trees and shrubs. In 
