1925] Efficiency of Birds in Destroying Larvce of Corn Borer 43 
except that the cornstalks showed no trace whatever of infes- 
tation by the European corn borer. Spring examinations showed 
that whereas birds had fed extensively on larvae in the infested 
stalks, there were only one or two shallow incisions that might 
be credited to birds in the stalks that were entirely free from 
infestation by this insect. These uninfested stalks were, there- 
fore, probably examined by the birds but the experiment showed 
that they were soon undeceived as to the fact that these stalks, 
although so much like the nearby infested ones in appearance, 
contained no larvae of the corn borer. Field observations have 
shown that birds also feed in the spring on the pupae of this insect, 
the nature of the feeding being similar in every respect to that 
described in the case of their feeding on larvae. In some cases 
portions of the pupae remain in the burrows of the insect as if 
the birds were not entirely pleased with the change that its 
food supply had undergone. 
These studies have been confined mostly to the feeding by 
birds on the larvae of the European corn borer in the fall, winter 
and spring, at which time the insect is in overwintering quarters 
within the host plant, because no such extensive feeding has 
been observed during the growing season. Adults of the insect 
are active only at night, resting during the day on the under 
sides of leaves unless disturbed when their flight is short and low 
and is to the nearest cover from the seat of disturbance. The 
larvae for the greater part of their lives feed hidden within the 
food plants, leaving their burrows infrequently except during 
the warmer nights of midsummer. It is known, however, that 
birds readily take the adult of the insect although observations 
seem to indicate that up to the present time they have not taken 
larvae from growing plants in any noticeable numbers. On two 
occasions, during studies of the capabilities of flight of the moths, 
birds took the flying insects to such extent as to interfere seriously 
with the success of the experiments. It is probable, therefore, 
that the reason that they do not feed more extensively on the 
moths is not because of any distaste for them, but because of 
the inactivity of the moths during the hours of sunlight. 
Since the larvae of the European corn borer in the over- 
wintering condition are nearly destitute of hairs and the skin is 
