SHUCK PROTECTION FOR EAR CORN. We 
Tasie I1V.—Relation of the shuck covering of corn to the increase in weevil infestation 
during storage. 
Percentage of ears 
infested. | Increase 
or 
Kind of shuck covering. a ier | aecrease 
during 
October, | August, 
1O15 ee eeroTo una |asHOraze: 
Of the ears in poor-shucks, 52 per cent were infested in 1915 and 97 
per cent in 1916. The infestation in 1916 was 45 per cent greater 
than in 1915. Of the ears in good shucks with wormholes, 38 per 
cent were infested in 1915 and 55 per cent in 1916. The infestation 
in 1916 was 17 per cent greater than in 1915. Of the ears in good 
shucks without wormholes, 9 per cent were infested in 1915 and 4 per 
cent in 1916. The infestation in 1916 was 5 per cent less than in 
1915. 
It seems a significant fact that during the period of storage the per- 
centage of weevil-infested ears increased decidedly in poor shucks 
and in good shucks with wormholes, but there was no increase in the 
percentage of ears infested in good shucks without wormholes. These 
data, coupled with the fact that no evidence could be found showing 
that weevils attempt to cut the shucks, indicate that the right kind 
of shuck covering is an effective barrier to this class of insects. 
LABORATORY INVESTIGATIONS. 
It is probable that the insects in seeking their food follow the line of 
least resistence. Under ordinary field and storage conditions they 
naturally attack the ears with least protection first and successively 
attack those with greater protection as the demand for food increases. 
While the investigations discussed on the preceding pages show that 
the better class of shuck protection successfully resisted insect damage 
under existing conditions, it is natural to suppose that insects which 
can eat the hardest kernels (fig. 3) of corn would also cut their way 
through the protecting shucks if sufficiently urged by hunger. With 
ordinary field and storage conditions it has always been possible 
for weevils to find some food, and for this reason it was not necessary 
to force a way to the corn in the best shucks in order that they might 
avoid extinction. With complete success in the breeding of ideal 
shuck coverings this last condition might arise, and it is desirable to 
know whether the acquired shuck coverings would prevent infestation 
under such conditions. To determine this point a number of weevils 
were confined in properly ventilated jars with ears of corn in good 
shuck coverings, but with no other source of food. The test was 
