Bee. io, 1917 Breeding Sweet Corn Resistant to the Corn Earworm 569 
INSTINCTS OF THE MOTHS 
That the number of larvae found in the ears of the different progenies 
shows significant differences suggests that the moths exercise a choice 
in depositing their eggs. It is possible to go a step farther and by exam¬ 
ining the average amount of damage inflicted by each earworm to deter¬ 
mine whether some progenies form a more suitable medium for the larva 
than others. It would seem that some allowance might have to be made 
for the crowding of the larvae and their cannibalistic tendencies, both of 
which would tend to reduce the damage per larva in ears with a large 
number of larvae. It is found, however, that in spite of these factors 
the correlation between number of larvae and damage per larva is posi¬ 
tive instead of negative—that is, on the average the more larvae there 
are in an ear the greater is the damage done by the individual larva. 
In the light of our present knowledge this would seem to indicate that 
the instincts of the moth are in accord with the requirements of the 
larva. In other words, the moth deposits more eggs on the plants most 
acceptable to the larvae. The only alternative explanation that suggests 
itself is that the larvae desert ears that are distasteful to them. 
A further indication that the moths exercise choice in attacking plants 
is the closeness of the correlation between the extent of damage on first 
and second ears of the same rows. Since this interprogeny correlation 
is closer than that between damage and prolongation, the most effective 
protective character measured, it follows that the close correlation be¬ 
tween the damage of first and second ears does not result merely from 
the fact that both have a similar prolongation. 
It might be urged that, since the two ears on a plant frequently come 
into silk simultaneously, there would be a tendency toward similar infes¬ 
tation. To test this point, the interprogeny correlation between the 
number of days that elapsed between the silking of first and second ears, 
and the difference in the number of larvae found in first and second ears 
was calculated. The correlation was 0.24+0.10. This correlation, 
while in the right direction, is too low to explain the similarity of infesta¬ 
tion of first and second ears, and may be the result of chance. 
If it is correct to assume that a great part of the immunity that has 
been secured has come about through a correlation between husk 
characters and some protective character or characters not recorded, 
it would not be surprising if there were similar correlations between 
long husks and characters of field varieties that are undesirable in a 
table com. 
, The progenies differed widely in depth of grain and tenderness, but 
those selected for propagation seem to compare favorably in palatability 
with their sweet ancestors. Sweet varieties have a larger percentage of 
sugar than field varieties and the transformation of sugar to starch is 
