LEriDOPTERA. 291 



the posterior extremity of the body are brown, with yellow mar- 

 gins, and are covered with raised orange-colored dots. The 

 chrysalis, which is not contained in a cocoon, is about two inches 

 long, of a dark chestnut-brown color, rough with little elevated 

 points, particularly on the 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 forepart of its body just before 

 the moth makes its escape. 



Dryocampa, oak or forest caterpillar, is a name originally ap- 

 plied 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 f.om 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 1 slender, and threadlike, but not flexible, and pro- 

 ject in the manner of horns. The most common of these cater- 

 pillars 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, pro- 

 ceed 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 finished 

 their meals, they cluster closely together along the twigs and 



