THE BROWN-TAIL MOTH 119 



of the female. The egg mass is elongate and is decidedly 

 convex or ridged. 



The eggs hatch in about three weeks, about the first of 

 August. (Those at laboratory hatched July 31 to August 

 4, 1905. Were observed hatching at Rochester August 10, 

 when almost all had hatched.) The young caterpillars feed 

 upon the surfaces of the leaves, skeletonizing them, and 

 when abundant causing the foliage to turn brown, as if 

 blighted or scorched by fire (Fig. 17). At first they feed 

 upon the leaf which bears the egg mass, but soon wander 

 to others, returning at night to the original leaf. The little 

 caterpillars are but a twelfth of an inch long when they 

 first emerge, but in about five days they molt for the first 

 time, after which they are about one fifth of an inch long. 

 A week or so later a second molt occurs, though often this 

 is within the winter web during the fall. Early in Sep- 

 tember the young caterpillars instinctively commence to 

 weave the nest or web, their winter home. It is made of 

 the leaves upon which they have been feeding, usually in- 

 cluding the old egg mass at the tip of the twig. The form 

 and shape" of the web varies with the position and the 

 materials available. Exit holes are left open so that the 

 caterpillars may go in and out as long as the weather is 

 propitious, but are usually closed during the winter. 



Compared ivith the Gypsy Moth. — Inasmuch as the 

 brown-tail and gypsy moths both were imported into the 

 same region in Massachusetts and have spread simultane- 

 ously, they are very commonly confused. ''That they were 

 both transported across the Atlantic to the same locality by 

 totally dissimilar agencies, ' ' as remarked by Mr. Kirkland^ 

 ''must stand as one of the remarkable entomological events 

 of the century just closed." And, it might be added, fur- 

 nish the strongest evidence of the need of more rigid legis- 

 lation against and inspection of all importations, either for- 

 eign or interstate, which may harbor insect pests. In view 

 of this common confusion, a comparison of the stages and 

 lives of these two insects was prepared for a recent bulletin 

 (121) on the gypsy moth, and is here reprinted: 



1 Report Massachusetts Horticultural Society, 1902. 



