302 Eeport of the Entomologists of the 



molt they measure from one and onc-lialf 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 Eitch.^^ 



"The caterpillar, after it has forsaken its nest and is Avandering about, is 

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

 color, tinged low down on each side with greenish-gray, and is everywhere 

 sprinkled over with black points and dots. Along its back is a row of ten or 

 eleven oval or diamond-shaped white spots, which are similarly sprinkled with 

 black points and dots, and are placed one on the fore part of each segment. 

 Behind each of these spots is a much smaller white spot occupying the 

 middle of each segment. The intervening space is black, which color also 

 forms a border surrounding each of these spots, and on each side is an ele- 

 vated black dot, from which arise usually four long, black hairs. The hind 

 part of each segment is occupied by three crinkled and more or less inter- 

 rupted pale orange-yellow lines, which are edged with black. And on each 

 side is a continuous and somewhat broader stripe of the same j'ellow color, 

 similarly edged on each of its sides with black. Lower down on each side is 

 a paler yellow, or cream-colored stripe, the edges of which are more jagged 

 and irregular than those of the one above it, and this stripe also is bordered 

 with black, broadly and unevenly on its upper side and very narrowly on its 

 lower side. The back is clothed with numerous fine fox-colored hairs, and 

 low down on each side are numerous coarser whitish ones. On the under side 

 is a large, oval, black spot on each segment, except the anterior ones. The 

 legs and pro-legs are black and clothed with short whitish hairs. The head is 

 of a dark bluish color, flecked with numerous black dots and clothed with 

 short blackish and fox-colored hairs. The second segment, or neck, is edjred 

 anteriorly with cream wliite, which color is more broad upon the sides. Tht 

 third and fourth segments have each a large black spot on each side. The 

 instant it is immersed in spirits, the blue color of caterpillar vanishes and 

 becomes black." 



By referring to Plate XXII, fig. 2, the difference in the dorsal 

 markings of the two common species of tent-caterpillars will be 

 plainly seen. The caterpillar on the left is an apple tree tent- 

 caterpillar, the other two are forest tent-caterpillar?, the one on 

 the right being a lateral view. All are nearly full-grown and 

 are natural size. 



The cocoon. — The cocoons are made of coarse white silk which 

 soon becomes discolored by the weather. In size and shape they 



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



