94 
BULLETIN 1476, U. S. DEPARTMENT OE AGRICULTURE 
Cage experiments which were conducted at Sandusky, Ohio, dur- 
ing 1924 to obtain information upon the percentage of larval estab- 
lishment and survival, and the causes contributing thereto, showed 
that an average of only 5.87 per cent of the eggs developed into 
larvae which became established in their host plant and survived 
to at least the third instar, in cases where such eggs were deposited 
upon growing corn plants (dent, flint, and sweet corn) by females 
temporarily confined in large cages while the eggs were being de- 
posited. These cages were removed immediately after the deposi- 
tion of the eggs to allow for the subsequent development of the insect 
and its host plant under natural conditions. Based upon the total 
larvae hatching in this series, an average of 8.36 per cent of the 
larvae became established in their host plant, as shown in Table 29, 
and reached at least the third instar before they were dissected 
from the plant. 
Table 29. — Summary of experiments of larval establishment and survival of the 
European corn borer at Sandusky, Ohio, 1924 
Type 
Variety 
Larvae under observation 
Total larvae 
ered 
recov- 
Per cent 
of recov- 
Date hatched (1924) 
Number 
Number 
Per cent 
ery for 
type 
Flint 
No data _. 
July 17 to July 30 . 
Aug. 8 to Aug. 12.. 
July 17 to Aug. 1__ 
Aug. 5 to Aug. 6__ 
Aug. 5 to Aug. 7__ 
July 17 to July 30 . 
July 17 to July 30.. 
1,195 
658 
1,361 
576 
784 
1,169 
1,276 
82 
62 
108 
86 
100 
96 
53 
6.86 
9.42 
7.94 
14.93 
12.76 
8.21 
4.15 
} 7.77 
1 
Do 
Dent 
do 
Do 
Do 
Claridge, high per cent grain. _ 
Claridge, low per cent grain.. 
[ 10.80 
} 6.09 
Do 
Total 
7,019 
587 
Average. 
8.36 
'"" 
Of the total of 587 larvae shown as recovered in Table 29, defi- 
nite records are available concerning the instars of 474 individuals 
in this group as follows : Thirteen larvae were in the third instar, 
219 larvae in the fourth instar, 132 larvae in the fifth instar, and 
110 larvae were mature. The remaining larvae recovered, 113 in 
number, had migrated to adjacent corn plants, and no records are 
available concerning the instars they represented. Close observa- 
tion of the young larvae used in this experiment showed that the 
greatest mortality occurred during the first and second instars and 
was attributable to a variety of causes, the most important of which 
appeared to be desiccation, starvation, and drowning. 
Complete records are not available pertaining to the number and 
percentage of eggs used in this experiment which failed to hatch or 
produce larvae. This information is available, however, for a por- 
tion of the eggs, 3,181 in number, and in this group 23.76 per cent 
were missed during their incubation period, presumably blown from 
the plants by the wind, 3.83 per cent failed to hatch, and 2.33 per cent 
dried up — a total egg mortality of 29.92 per cent. Assuming that 
the same rate of egg mortality was sustained by all the eggs used in 
this experiment, the total establishment and survival to at least the 
third instar, based upon the number of eggs in the experiment, 
equaled 5.87 per cent. 
