BOMBYCIDS. 103 
ing creature with large coral-red tubercles on the forward part of its 
body, yellow ones on its back, and smaller blue ones on its sides and 
about its head, all covered with short black bristles. It clasps the 
bough or twig on which it rests with a wonderful tenacity, and if 
placed on one’s finger the grasp of its fleshy feet with their minute 
hooks is very noticeable. It has a peculiar odor, both in the larva 
and the moth state, which may be of some protection to the animal. 
Toward the end of September the caterpillar constructs its coarse, 
brown, elongated cocoon, which is usually attached on one side to a 
twig or branch. This cocoon is composed of two parts, consisting of 
a loose, wrinkled outer covering and a well-shaped and dense inner 
pod, with fine floss silk separating the two, which are both loosely 
Section of cocoon of Attacus cecropia. 
spun at one end to enable the moth to make its escape. ‘There is 
frequently a marked difference between the cocoons found on trees 
and shrubs on high ground and those taken from low bushes and 
shrubs in swampy districts. The latter are frequently two or three 
times as large externally as the upland variety, and have a large 
amount of the floss silk between the outer and inner coverings. 
This variation I cannot explain, and have noticed no difference in 
the moths emerging from the two varieties of cocoons other than 
that the swamp-inhabiting specimens appear larger and richer in 
coloring than their upland relations. Sometimes the cocoons of these 
species are to be found in large numbers. In the suburbs of Chicago 
they may be seen on the shade trees in dozens and sometimes in hun- 
dreds ; and I have known two men to colleet a bushel of them in 
