370 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
creamy yellow, inside of which is a row of blue spots. The wing ex- 
panse ranges from 2 to nearly 3 inches. The full-grown larva, or 
spiny elm caterpillar, is about 2 inches long; the head bilobed and 
black, and the body black thickly sprinkled with whitish dots. The 
back has a black longitudinal line interrupted by a row of seven or 
eight reddish spots, and each segment has a transverse row of black, 
branched spines. The abdominal legs are reddish (fig. 70, #). 
This species is widely distributed throughout the subarctic regions 
of North America, and also in Europe and Asia. Elm, willow, and 
poplar are its food plants, and sometimes it is abundant locally, prin- 
cipally on shade and ornamental trees and along fence rows. The 
adults hibernate during the winter and leave their hiding places dur- 
ing the first warm days of spring. The eggs are deposited in clusters 
around the smaller twigs at the time the foliage is nearly full grown, 
or later. There are two generations a year, and the larvae may be 
found from May to September. They are gregarious until nearly 
full grown and usually defoliate one branch before moving to another. 
The full-grown larva of the viceroy (Basilarchia archippus 
(Cram.)) is about 114 inches long. The head is large, bilobed, and 
pale green, and the face grooved vertically. The body has segments 
1 and 2 pinkish to brownish, segments 3 to 6 and sides of 7 brown- 
ish or greenish, top of segments 7 and 9 and nearly all of 8 pale 
pinkish or whitish, the sides of 9 and nearly all of the last three seg- 
ments brownish or greenish. There is a pale flesh-colored or whitish 
stigmatal stripe. On the top of the second thoracic segment are two 
barbed, club-shaped, brown tubercles, and on the top of other seg- 
ments are pairs of smaller tubercles armed with blunt spines. The 
shading is somewhat variable (fig. 70, 7). 
The species occurs from the Gulf States to Canada and British 
Columbia. Its larvae feed on poplar and willow and, although com- 
mon, probably are never serious pests. The adults are found from 
June to September, and the larvae are active from spring until fall. 
The partly grown larvae hibernate individually, each in a rolled leaf 
attached to a twig of the food plant. There are probably at least two 
generations in the United States. 
Basilarchia arthemis (Drury) and B. astyanax (F.) resemble very 
closely B. archippus in the larval stage. They commonly feed on 
apple, basswood, and wild black cherry. B. arthemis occurs through 
the Northeastern States, Quebec, and Ontario, and B. astyanaa is gen- 
erally distributed from southern Canada south through the United 
States. Like B. archippus they are sometimes very common locally, 
and they have a similar life history. 
The full-grown larva of Asterocampa celtis (B. & L.) is bright 
pea green and about 114 inches in length. The head is broad, varying 
in color, and armed above with two prominent branched horns or 
antlers. The body tapers toward both extremities, the anal end with 
two shghtly elevated projections. The top of the body is marked with 
a longitudinal row of yellow spots, and on each side there are three 
yellow lines. 
The full-grown larva of Asterocampa clyton (B. & L.) is bright 
green and about 114 inches in length. The head is shiny bluish green 
and armed with broad branched antlers. The body is marked with 
a yellowish dorsal stripe, and a deep blue stripe on each side of it 
