300 THE GYPSY MOTH. 



tions agreed very closely, except that those which hatched 

 latest did not require as many days in their molts, and there- 

 fore reached the adult stage as soon as the others, although 

 marked variations occurred among the individuals of each 

 hatch (Plate 43). Some grew faster than others, while some 

 appeared to eat about the same amount as others and yet did 

 not grow as rapidly. 



Description of the Larva or Caterpillar. 



The following descriptions were prepared from the study 

 of from twenty-five to fifty caterpillars in each stage : — 



First Larval Stage. — The larva, when first hatched, is 

 3,6 mm. (about fourteen hundredths of an inch) in length, and 

 the head is .6 mm. (about twenty-three thousandths of an inch) 

 in width and somewhat thicker than the body, shining black, 

 with a few (about forty) pale-yellow hairs scattered over the 

 surface, the longest of which are not quite equal to the width 

 of the head. There are a few additional hairs on the mouth 

 parts. The body is more or less cylindrical, slightly taper- 

 ing toward the posterior part which is blunt and rounded. 

 When first hatched they are a pale brownish-yellow, with a 

 brown spot on the forward side of segments four to twelve 

 inclusive, on the subdorsal line of each side, but the ground 

 color jrrows darker within a few hours. The subdorsal tuber- 

 cles of the second segment (first after the head) are elon- 

 gated laterally and joined at the dorsal line. These are of 

 a dark-brown color. The lateral tubercles of this segment 

 are fused, forming one very large lateral tubercle on each 

 side, which extends obliquely out and forward. The third 

 and fourth segments have three tubercles on each side, one 

 subdorsal, one lateral and one stigmatal. The remaining 

 segments, except the last, have large subdorsal and lateral 

 tubercles, the latter being so large as to fuse more or less 

 completely with those above them. There are three nearly 

 equal-sized tubercles on each side of the last segment, so 

 arranged as to form an arched row around the posterior end 

 of the animal. 



The insect at this stage has two kinds of hairs arising 

 from the tubercles,. the first of which (Plate 48, Fig. 8) is 

 about as long as the thickness of the body, of a pale-brown 



