10 BULLETIN 598, U. S. DEPARTMENT OF AGRICULTURE. 
Bighth feeding stage (including only larve that spun cocoons at end of this 
instar): Minimum 19 days, maximum 29 days, average 23.29 days; 7 larve 
reared. 
Ninth feeding stage (until spinning of cocoons): Minimum 18 days, maxi- 
mum 26 days, average 20.95 days; 188 larve reared. 
The period covered by the rearing records in 1915 began when the 
larvee under observation hatched, on July 17, and continued until 
time of spinning cocoons, which extended from September 17 to 
October 10. In 1916 the earliest larvee hatched June 30, and the 
first cocoon under observation was spun September 24 and the latest 
October 10. 
DURATION OF PREPUPA PERIOD. 
The larva period in the cocoon at North East, Pa., in 1916 aver- 
aged between 7 and 8 days. Of 19 larve which spun cocoons on 
September 24, 25, and 26, 10 pupated in 7 days and 9 in 8 days. 
HABITS. 
THE LARVA. 
Larve from the same egg mass hatch almost simultaneously and 
upon hatching eat the greater part of the eggshells. They are gre- 
garious in the early stages, and even in the later stages molt together. 
During the first four stages they feed gregariously, beginning to scat- 
ter in the latter part of the fourth. If during the first three stages 
a larva is separated from its fellows and is placed on a separate leaf 
or shoot, it will invariably find its way back to the others within a 
few hours. When one leaf or shoot is stripped the larve move in 
mass to another, often to another part of the tree. 
After the fifth stage the larvee scatter more or less and are solitary 
except about molting time. Often they migrate to trees quite a dis- 
tance from the one on which the colony started. After the last molt 
the larvee scatter widely. 
The molting of the majority of larve from a given egg mass is 
almost simultaneous, and at this time the gregarious habit is most 
pronounced. Even after larve have scattered over a tree they come 
together to molt. A short time before molting a silken mat is spun 
upon which the larve rest for about a day before the early molts 
and sometimes. for several days before later ones. This molting mat 
is spun upon a leaf or bunch of leaves, and sometimes before the later 
nvolts on the side of a branch or tree trunk. At each molting period 
there are often a few larvee which fall behind and fail to molt with 
the rest. These invariably develop very slowly and usually do not 
mature. 
