BIOLOGICAL STUDIES OF THE GKEEN CLOVER WORM 
13 
October 29. On November 14, however, many of them were observed 
to be dead on the outer leaves, having been killed bv heavy frosts 
that occurred during; the preceding three nights, although a few 
larvae were still alive in protected places. Subsequently no living 
larva? were to be found, and their disappearance was attributed to 
the cold weather. At Nashville, Tenn., eight healthy larva' were 
placed in the field on an alfalfa plant, under a wire cage, and a 
thermograph was installed near by. A minimum temperature of 
34° F. killed three of these larvae the first night. The next night 
two more succumbed to a temperature of 31° F., but the remaining 
three survived a temperature of 26° F. and two of them eventually 
pupated, one later emerging as a moth. 
PREPUPAL STAGE 
When mature, the larva stops feeding, descends to the earth, 
and on or partly beneath the surface thereof constructs an oval 
cocoon (fig. 13) of earthen particles or bits of rubbish and leaves 
loosely webbed together. If no debris be present, plain silken cases 
are spun, protected on one side by some object. Within the cocoon 
the larva lies at first in a curved position, which gradually becomes 
less pronounced as the body contracts. This period lasts from one 
to six days, with an average of about two days in warm weather. 
PUPAL STAGE 
The pupal stage ordinarily covers a period of from 7 to 24 days, 
as shown in Table 8. data for which were obtained from 20 pupae 
reared from May 
20 to November 
3. There is evi- 
dence, however, 
that this species 
sometimes hiber- 
nates as a pupa. 
From a number 
of pupae formed 
between October 
8 and 19 and ex- 
posed to outdoor 
conditions, the 
moths failed to 
emerge at the 
usual time; but 
when these were 
brought indoors 
late in Novem- 
ber one adult 
emerged, having 
passed a pupal period of 42 days, and another came out Decem- 
ber 2 after a pupal period of 44 days. 
Fig. 13.— Cocoons with pupae of the green clover worm partly out of them 
