55 
water. The eggs had been laid about eighteen hours and were left 
under the water for three days. At the end of this time 8, or 23 per 
cent, had hatched and 3 larvie remained, drowned in the water, while 
the other 5 had crawled up into the air and escaped. From this it is 
evident that the short periods during which eggs are exposed to 
extreme moisture in nature can have but little influence on them. 
EGGS DESTROYED BY STORMS. 
A very important factor, however, and one which undoubtedly 
causes the destruction of immense numbers of eggs, is the mechanical 
force of the rain during violent storms. Although they are rather 
firmly attached, the combined effects of rain, wind, and sandy parti- 
cles washed against the plants removes many eggs. On two occasions 
during the spring. May 16 and May 29, plants in the laboratory gar- 
den known to have had eggs on them were examined after the rains 
and most of the eggs were found to be missing. Regarding field con- 
ditions, no positive data are at hand, but the unusual scarcity of eggs 
on corn after hard rains was evident on several occasions. 
EFFECT OF SUN ON EGGS. 
There is an opinion held among many planters that a large number 
of eggs, when laid on exposed portions of tlie plant, are destroyed by 
the rays of the hot midsummer sun. This led us to try the experi- 
ment of subjecting eggs to the direct rays of the sun. On August 30 
a lot of 20 eggs which had been laid on a dried cotton leaf were pinned 
high up on a cotton plant, where they were in continuous sunshine 
during the day. All hatched after the normal period. Again, a few 
days later a moth was caged over a few leaves of a growing cotton 
plant, and some 50 eggs were laid on the upper sides of the leaves. 
After this the cage was removed and the leaves slanted so as to receive 
the perpendicular rays of the sun. The eggs were in no way injured, 
however, and practically all of them hatched normally. 
THE LARVA. 
When the young larva hatches from the e^g it is scarcely over a 
millimeter in length, and during growth it molts or sheds the skin six 
times before becoming a pupa or chrysalis. Very exceptionally one 
of these molts may be omitted, the bollworm pupating after only five 
molts. Each successive instar is larger, and the larva grows more 
and more rapidly as it nears maturity. The larvse were carefully 
studied by Mr. Girault during the course of his breeding work, and 
the technical descriptions included in the following account have been 
prepared by him from notes made at that time. 
