PROGRESS REPORT ON THE EUROPEAN CORN BORER 133 
from the water. A small percentage of overwintering larvae con- 
tained in floating cornstalks survived, and one produced a moth, after 
being in the water for 36 days during the spring. Of the free larvae 
submerged in the water for 14 days during the month of May, 40 
per cent survived and eventually developed into moths. In this 
and in similar experiments many larvae, which appeared to be dead 
when taken from the water, revived after a period of several days. 
It was, therefore, necessary to keep all larvae used in the experiments 
under observation until they revived or until decomposition began. 
Naturally these larvae which were retained for observation could 
not be returned to their natural position in the stalks of plants, 
but were kept in screen wire cages containing sections of cornstalks. 
The cages were placed in an outdoor insectary. It is believed that 
the chances of dispersion of infested material by water is greater 
during the spring than at any other period. Hence the resistance of 
larvae to drowning in submerged or floating material at this time is 
especially important. In these experiments old cornstalks remained 
afloat in fresh water for a maximum period of 62 days in the spring, 
or until taken from the water. Partly matured cornstalks placed 
singly in fresh water during the last week in August floated for an 
average period of 40 days and a maximum period of 68 days before 
sinking. These cornstalks were partly green, as is usual with corn- 
stalks taken from the field at this time of year. The upper portions 
of the stalks were dry and the lower portions were green and suc- 
culent. Bundles of cornstalks similar to those just described, placed 
in fresh water on September 18, floated until they were frozen in the 
ice just prior to December 1, a period of 73 days. Small stalks and 
pieces of stalks sank sooner than entire stalks bearing ears. It 
appears, therefore, that in the spring or fall cornstalks may float for 
a sufficient period to become widety dispersed. 
A small percentage of first-generation or summer larvae survived 
and eventually developed into moths from cornstalks completely 
submerged in water for 42 hours. Larvae of this generation also 
survived and produced moths from stalks floating in water for 163 
hours, or nearly 7 days. Free larvae survived and produced moths 
after submergence in water for 48 hours. 
\Yhen cornstalks containing second-generation larvae were sub- 
merged in water during late August, certain of the larvae survived 
an exposure of 48 hours, whereas two weeks later they survived a 
similar treatment of 72 hours in submerged and" also in floating corn- 
stalks. During the first week in October certain of the larvae sur- 
vived from cornstalks floating in water for 120 hours, indicating 
that their resistance to drowning increased with the approach of the 
inactive period. Free larvae of this generation survived when sub- 
merged in water for 72 hours during the last week in September. 
First-generation pupae in cornstalks which had been submerged 
in water for 68 hours, and in cornstalks which had floated in. water 
for one week, produced adults. Free pupae of the first generation 
submerged in water for 67 hours produced a single adult, and free 
pupae of the second generation receiving a similar treatment for 
24 hours produced no adults. Free pupae of the first generation 
floating in sea water for two weeks produced adults during the first 
7 days. Pupae in fresh water produced adults for 6 days. 
