392 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
times with black markings, the body greenish white, often with black 
dorsal spots patterned as the hair pencils in other species. Just prior 
to pupation the larva becomes much darker, varying from brown to 
blackish. This species is recorded from Canada, northern New Eng- 
land, New York, and northern [hnois. The favored food plant is 
poplar. Other authors also list willow and birch. The moths emerge 
in June and July, the larvae are found in August and September, 
and the winter is passed in the pupal stage in a frail cocoon on the 
ground. 
Figure 78.—Larva of the cottonwood dagger moth (Acronicta lepusculina). 
The American dagger moth (Acronicta americana Harr.) is the 
largest species of the group. The full-grown larva is about 2 inches 
in length, clothed in fine, yellowish hairs, and bears a pair of long, 
black hair pencils on the backs of the first and third abdominal seg- 
ments and a single one on the eighth. The head is shining black; the 
body greenish white above with a broad, black stripe on the top of the 
ninth and tenth abdominal segments, and a broken stigmatal, black 
stripe and traces of a subdorsal one. The body is blackish underneath. 
This species occurs throughout the eastern part of the United States 
and Canada. Inthe Northeastern States itis often very common. Its 
food plants include apple, basswood, boxelder, chestnut, elm, maple, 
oak, willow, and other deciduous growths. The moths emerge from 
May to July, the larvae are found from June to October, and the 
winter is passed in the pupal stage in a cocoon composed of silk and 
hairs. 
_Acronicta impressa Wikr. and A. distans (Grote) are possibly a 
single species. The full-grown larvae are somewhat variable. The 
