F-519531 
Figure 93.—Larvae of Symmerista canicosta, the 
redhumped oakworm. 
1961. There are two generations per year. The orangehumped mapleworm, S. 
leucitys Franclemont, occurs in the Northern States and southern Canada where it 
feeds principally on sugar maple. Its life history and habits are similar to those of 
the redhumped oakworm. It is distinguished from the latter by an orange headcap- 
sule and hump and three fine, black dorsal stripes (/0). 
The variable oakleaf caterpillar, Heterocampa manteo (Doubleday), occurs in 
nearly all of the States and Canadian provinces east of a line drawn from western . 
Ontario through eastern Texas. Its hosts include a wide variety of deciduous trees. 
All species of oaks are attacked, but white oak is preferred. Other important species 
attacked include beech, basswood, paper birch, American elm, walnut, boxelder, 
persimmon, and apple (/3/8). The adult is ashy gray and has a wingspread of 37 to 
42 mm (fig. 94A). The full-grown larva is about 38 mm long with variable 
coloration. The head is large with two broad, lateral bands, the inner brown or 
black and the outer creamy white. The body is smooth, yellowish green with a pale, 
middorsal longitudinal line, and with more or less reddish-brown coloration on each 
side bordered laterally by a creamy-yellow stripe, below which is a yellowish, 
stigmatal stripe (fig. 94B). 
Pupation occurs in early spring, and the adults appear from early May in the 
South to late May or early June in the North. Eggs are deposited singly on the 
leaves, each female laying up to 500. Young larvae skeletonize the lower surfaces of 
the leaves and older ones eat entire leaves, except the larger veins. Mature larvae 
move to the ground and spin cocoons in the litter or top soil. The larvae spray a 
chemical mixture containing formic acid, when disturbed. The mixture is capable 
of blistering the skin of humans (656). Winter is spent in the prepupal stage. There 
are two generations per year in the South and one in the North. 
Trees of all sizes are attacked, and heavy defoliation may occur anywhere in the 
insect’s range, especially in the South. Some outbreaks have been extensive, 
covering thousands of square kilometers and extending for hundreds of kilometers 
(1179). Tree mortality has usually not been serious, however, since most trees of 
sapling size or larger are able to withstand several years of extensive defoliation. 
The saddled prominent, H. guttivitta (Walker), occurs in southeastern Canada 
and throughout the Eastern United States. Beech, yellow birch, and sugar maple are 
220 
