45 



given by him. The caterpillars just after leaving the eggs 

 measure on the average 2 mm. in length. They are dull black in 

 color with long grayish-white hairs arising from numerous 

 minute tubercles. In a few days there is a slight change in color. 

 The middle of the body becomes lighter, taking on a brownish 

 tinge, while the extremities remain darker. The tubercles also 

 become more distinct and a dark interrupted line conspicuous 

 along each side. These markings become more prominent as 

 the time for the first molt approaches. 



The first moli.— The first molt occurs from ten days to three 

 weeks after the caterpillars emerge from the eggs, the varia- 

 tion in time probably depending upon the abundance of the food 

 supply. Immediately after the first molt they measure about 

 one-half inch in length. There are two pale yellowish sub-dorsal 

 lines bordering the dark lines above referred to. These lines 

 become more conspicuous as the time for the second molt 

 approaches ; the dorsal spots are also indistinctly seen. 



The secofid moli. — This molt occurs from a week to ten days 

 after the first, when the length is about three-fourths of an inch. 

 A row of eleven cream-white somewhat diamond-shaped or club- 

 shaped spots extends the full length of the back. Also as Dr. 

 Riley states in the reference above given : ' ' The upper pale line 

 becomes yellow, the lower one white, and the space between them 

 bluish." 



The third molt. — The third molt occurs about a week to ten 

 days after the second. The caterpillars measure about one inch 

 in length. There is little change in the markings except that 

 they become more distinct. 



The fourth molt. — Between the third and fourth molts is the 

 most rapid-growing period of the larval life. After the fourth 

 molt they measure from one and one-half to two inches in length. 

 Last spring caterpillars that measured two inches were quite com- 

 mon and a few were found that measured two inches and a 

 quarter. 



The following technical description is by Dr. Asa Fitch. '^ 

 " The caterpillar, after it has forsaken its aest and is wandering about is 

 an inch and a half long and 0.20 thick. It is cylindrical and of a pale blue 



'* Fitch. Fifth Report on the Insects of New York, p. 821. 



