small spots are on abdominal segments two to seven and four on 
the eighth. P. cresphontes Cramer feeds on prickly ash in the 
Northern States. 
Graphium marcellus Cramer, the zebra swallowtail, feeds on 
pawpaw. / 
FAMILY NYMPHALIDAE 
BRUSH-FOOTED BUTTERFLIES 
This family contains some of our most common butterflies. The 
adults are medium to large and are distinguished by having the 
forelegs much reduced and without claws. Only the middle and 
hind pairs are used for walking. The head of the caterpillar is 
usually bilobed, the tips of the lobes often supporting branched 
spines, and the body is spiny or bears fleshy, hair-covered warts. 
The chrysalids are naked and are usually suspended by the 
cremaster. 
Polygonia interrogationis (F.), the question-sign feeds on elm, 
oak, and hackberry in eastern America, especially on sprout 
growth along roadsides. Full-grown caterpillars (fig. 104) are 
brownish with yellow mottlings and are about 37 mm. long. Each 
body segment bears a transverse row of light-colored branched 
spines. There are two generations per year. P. comma (Harr.), 
the comma butterfly, occurs on elm, nettle, and hop from Canada 
to the Carolinas and Texas. Full-grown caterpillars are yellowish 
white, and each body segment bears a transverse row of branched 
spines. 
Nymphalis j-album Bdv. and LeC. feeds principally on gray 
and paper birches, but also on poplar and willow in Canada and 
south to Pennsylvania in the Eastern States. Caterpillars have 
black heads, the body is reddish to blackish on the dorsum with 
F-519524 
FicurRE 104.—Larvae and chrysalis of the butterfly, 
Polygonia interrogationis, the question-sign. 
292 
