302 Report oF THE ENTOMOLOGISTS OF THE 
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 nest and is wandering 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 yellow 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 cf 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 edged 
anteriorly with cream white, which color is more broad upon the sides. The 
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-caterpillars, 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 
grt 
18 Fitch. Fifth Report on the Insects of New York, p. 821. oy, 
