THE SWEET-POTATO LEAF-FOLDER. 7 
moths kept in confinement. The first lot were from larvae that issued 
on June 21. Eight of these spent 13 days in the larva stages, and 
2 pupated 14 days after issuing from the egg. The averages of the 
daily maximum and minimum temperatures for this period, taken 
from a self- registering thermograph, were 95.3° and 72.6° F., respec- 
tively. 
The second lot of larvae were reared during August. They issued 
on August 3. Two pupated 13 days after issuing from the egg, 
while two required 14 days, one 15 days, and six 16 days for the 
larva stages. For this period the average of the daily maximum 
temperatures was 90° F. and the average of the daily minimum tem- 
peratures 72.8° F. 
In the case of the larvae reared during August observations were 
made to determine the length of time required for the various in- 
stars. Because of the fact that after the first five molts the larva 
usually devours all of the cast skins, with the exception of the 
tougher portion from the head, it js rather difficult to determine the 
exact time of molting, especially in the early stages. The time spent 
in each of the 6 instars was, however, ascertained from 7 larvae. 
With two exceptions the periods were as follows : First instar, 3 days; 
2d, 3d, 4th, and 5th instars, 2 days each; 6th instar, 5 days. One 
larva spent 3 daj^s in the second instar and another only 4 days in 
the sixth instar. 
PREPARATION FOR PUPATION. 
After completing its growth the larva ceases feeding and con- 
structs a cocoon, within which it transforms later to the pupa. Dur- 
ing the period intervening between the time when the last food is 
taken and the time of pupation the larva undergoes a gradual 
change; it becomes shorter, the bluish-green color disappears, and 
the larva becomes sluggish. 
In the insectary during July and August the time required in 
preparation for pupation was, with few exceptions, two days. In a 
few cases three days were required. Under the heading " Hiberna- 
tion " the length of time passed in preparation for pupation by indi- 
viduals that complete their larval growth later in the season is given. 
PUPATION. 
In the field and in the insectary pupae normally are found in 
loose cocoons within the shelters made by the larvae. Larvae develop- 
ing after the latter part of August sometimes construct in confine- 
ment a somewhat different type of cocoon, which will be discussed 
later. 
The pupa period occupied from 6 to 9 days in the insectary 
during July and August. During September, 1915, two individuals 
