LEPIDOPTERA. 311 



the nolchcJ ridges, and the long spine at the end of the body, 

 enable the chrysalis to work its way upwards in the earth, 

 above the surface of which it pushes the fore part of its body 

 just bofore the moth makes its escape. 



Dryocampa^ oak or forest caterpillar, is a name originally 

 api)lied by me to certain insects, found sometimes in great 

 numbers on oak-trees, which then suflcr very severely from 

 their ravages. Of these caterpillars there are several kinds, 

 resembling each other in shape, and in the form and situation 

 of the thorns with which they are armed, but difi'ering in color, 

 and in the moths produced from them. They live together in 

 swarms, but do not make webs ; their bodies are cylindrical, 

 remarkably hard and stiff, naked or not hairy, and have, on 

 each ring, about six short thorns, or sharp points, besides two 

 on the top of the second ring, which are long, slender and 

 threadlike, but not flexible, and project in the manner of horns. 

 The most common of these caterpillars in Massachusetts is 

 black, with four narrow ochre-yellow stripes along the back, 

 and two on each side. It is found in swarms of several hun- 

 dreds together, on the limbs of the white and red oaks, during 

 the month of August. The eggs from which they proceed are 

 laid in large clusters on the under side of a leaf near the end 

 of a branch. The caterpillars are hatched towards the end of 

 July, but sometimes earlier, and at other times later. At first 

 they eat only the youngest leaves at the end of the branches 

 and twigs, and, as they grow larger and stronger, proceed 

 downwards, devouring every leaf, to the midrib and foot-stalk, 

 from one end of the branch to the other. They have their 

 regular times for eating and for rest, and when they have fin- 

 ished their meals, they cluster closely together along the twigs 

 and branches. If disturbed, they raise the fore part of their 

 bodies, and shake their heads to signify their displeasure. 

 When fully grown they measm'e about two inches in length. 

 Commonly in the early part of September, they crawl down 

 the trees and go into the ground, to the depth of four or five 

 inches, where they are changed to chrysalids. These resemble 

 the chrysalids of the imperial Dryocampa, but are much smaller, 

 and like them they remain in the ground throughout the win- 



