THE BROWN-TAIL MOTH 



113 



the time the maximum reached 80° Fahr. A record of the 

 caterpillars emerging from 10 nests of average size gave an 

 average of 375 per nest, the largest number being 444 and 

 the smallest 172. The webs vary greatly in size, however, 

 as Fernald and Kirkland found as few as 47 and as many 

 as 802 in a single web. 



An examination of the caterpillars in five winter webs 

 made during the winter of 1905 showed an average of about 

 25% dead. After the remarkable warm weather of Jan- 

 uary 21-23, 1906, a careful examination of nine nests was 

 made, having an average of 220 caterpillars each, of which 

 10% were dead, the smaller mortality possibly being due 



to the mild 

 winter up to 

 that date. 



It seems 

 quite probable 

 that were a few 

 unu sually 

 warm days to 

 occur in early 

 spring, so as to 

 cause the cat- 

 e r pil lars to 

 leave the webs, 

 followed by a 

 sharp freeze, 

 that many of 

 them might be 

 killed, as were 

 the forest tent 

 caterpillars in 

 1900 (see Bul- 

 letin 81, p. 11). 

 Considerable 



Fig. 8.— Small Brown-Tail Moth caterpillars emerging COmmeUt 11 a S 

 from the winter web and feeding on the arisen in the 



leaves of its snrface. 



