hairs at the posterior end of the abdomen (284). Full-grown lar- 
vae are dark brown and about 18 to 25 mm. long. The head and 
thoracic plates are yellowish and spotted with black. 
Male bagworm moths emerge in the fall, fly to the females, 
and mate. The female remains in her larval bag and deposits her 
eggs either in or outside the pupal case. Winter is spent in the 
bag in the egg stage and the eggs hatch during the following 
May or June. The larvae feed on the surface of leaves at first; 
later entire leaves are consumed. Mature larvae attach their bags 
to twigs (fig. 165) with silk, and pupate in them. There is one 
generation per year. 
The bagworm is most important as a pest on shade trees and 
ornamental shrubs growing in yards and hedges, along the streets 
of cities and towns, and in parks and other recreational areas. 
Large numbers of arborvitae and other conifers are lost each 
year as a result of complete defoliation. Many others only partly 
defoliated are weakened and rendered unsightly. Damage to forest 
trees is usually not very severe (444); however, heavy infesta- 
tions do occur occasionally in stands of cedar and black locust, 
especially in the Deep South. 
Low winter temperatures, bird predation, and parasitism by 
the ichneumonid, /toplectis conquisitor (Say), are often particu- 
larly effective in bagworm control. Handpicking and burning of 
overwintering bags is also helpful in control, especially on small 
trees and ornamentals ( 790). 
F-508522 
FIGURE 165.—Larval cases of the bagworm, Thyridopteryx ephemeraeformis, 
attached to the twigs of an infested tree. 
412 
