1925] Efficiency of Birds in Destroying Larvce of Corn Borer 41 
Mass., where birds did not feed on the larvae contained in the 
cornstalks of the experiment (table 3) although it was found in 
the spring of 1923 that they had removed a high per cent of the 
borers from a field of heavily infested cornstalks (table 2). 
From these instances it appears that birds might not be depended 
on to feed on corn borer larvae in cornstalks in the same locality 
each year. On the other hand, heavily infested localities are 
known, noticeably Medford, Mass., where birds have fed on 
overwintering larvae consistently in the springs of 1922, 1923 and 
1924. 
Throughout the infested area of Massachusetts there was 
very little corn standing in the field during the winter of 1923- 
1924. The condition of all the experiments was the same, there- 
fore, in that practically no cornstalks other than the experiments 
were to be found by the birds and for this reason there was no 
influence brought to bear, as far as the extent of feeding was 
concerned, by proximity of the experiments to infested cornfields. 
Because of the general scarcity of standing corn during the 
winter of 1923-1924 it might appear that a condition of con- 
centrated feeding on the experimental material might result. 
It does not seem that any such phenomenon took place, however, 
because in the experiments examined in the spring of 1924, in no 
case was the bird feeding found to be as extensive as on the 
TABLE NO. 4. 
The Extent of Bird Feeding on Experimental Material at Medford, Mass., 
on different dates in the Spring of 1924 . 
Date 
Examined 
Number 
of 
stalks 
Number 
of 
expected 
larvae 
Number 
of 
larvae 
recovered 
Apparent 
number 
taken 
by birds 
Apparent 
per cent 
taken 
by birds 
IV-4-24 
10 
155 
100 
55 
35-5 
IV-11-24 
10 
155 
73 
82 
53 - 
IV-17-24 
10 
155 
62 
93 
60. 
IV-24-24 
10 
155 
108 
47 
30.3 
V-2-24 
10 
155 
50 
I0 5 
67.7 
V-8-24 
10 
155 
32 
123 
79-3 
V- 1 5-24 
10 
155 
18 
137 
88.4 
