of the first generation appear in late May or June. Larvae of this generation are 
found in June and July. Adults of a second generation appear from late July to early 
September. This species is often abundant locally in the Northeastern States. 
Approximately 40 additional species in the genus Nematus have been recorded 
from eastern forests. Known hosts of a few species are as follows: black locust—N. 
abbotii (Kirby); black locust and honey locust—N. tibialis Newman, paper birch— 
N. viridescens Cameron and N. pinguidorsum Dyar; willow and possibly poplar— 
N. fulvicrus Provancher; poplar—N. hudsoniimagnus Dyar; hophornbeam-——N. 
ostryae (Marlatt); American hornbeam—N. carpini (Marlatt); alder—JN. 
erythrogaster Norton; poplar and willow—N. limbatus Cresson; and willow—N. 
oligospilus Foerster. 
Trichiocampus viminalis (Fallén), the poplar sawfly, an introduced species, 
occurs across southern Canada and the Northern United States. Its hosts are various 
species of poplar and sometimes willow. Full-grown larvae are orange-yellow, 
sparsely clothed with yellow hairs, and about 18 mm long. Each side of the body is 
marked with two rows of more or less rounded black spots. Those of the lowest row 
are small (fig. 195). 
x 
Courtesy Conn. Agric. Exp. Stn. 
Figure 195.—Larvae of the poplar sawfly, 7richiocampus 
viminalis, on leaves of poplar. 
Winter is spent in the prepupal stage in cocoons in the duff beneath the trees. 
Pupation occurs in the spring and the adults appear in May. Young larvae feed side 
by side on the leaves. 
Older larvae tend to scatter and eat all but the midribs and larger veins. They 
become full grown in June or early July. Some pupate and give rise to a second 
generation of adults in August; the remainder do not complete their development 
until the following spring. Carolina and Lombardy poplars grown for ornamental 
purposes may be seriously defoliated. 
The dusky birch sawfly, Croesus latitarsus Norton, is the most commonly 
encountered species in the genus, and occurs in eastern Canada and south through 
the Eastern States to Florida and west to Alaska, British Columbia, and Utah 
(1098). Its hosts are various species of birch, preferably gray birch. Full-grown 
larvae are yellowish green with shades of black and are about 24 mm long. There is 
a row of more or less distinct black blotches on each side and a series of black spots 
in the subspiracular area. 
406 
