THE SENATORIAL DRYOCAMPA. 405 



anterior extremity, ends behind with a long forked spine, 

 and is surrounded, on each ring, with a notched ridge, the 

 little teeth of which point towards the tail. Three of the 

 grooves or incisions between the rings are very deep, thus 

 allowing a great extent of motion to the joints, and these, 

 with the notched 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 before the moth makes its escape. 



Dryocampa, oak or forest caterpillar, is a name originally 

 applied by me to certain insects, found sometimes in great 

 numbers on oak-trees, which then suffer 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 differing 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. Fi 198 



The most common of these 



caterpillars (Fig. 198) 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 hundreds 

 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 



