Ly 
Of these, all but three were destroyed, probably by boys, 
the nests being torn down and the eggs missing. The three 
which escaped destruction were two wrens’ nests which had 
been built in boxes upon buildings, and a robin’s nest in a 
maple tree within ten feet of a chamber window. This 
wholesale destruction of nests discouraged several pairs of 
birds, and they disappeared from the neighborhood. Those 
remaining built new nests, and after a second or third at- 
tempt a few succeeded in rearing young. One nest of orioles 
escaped the general destruction, and the birds were busy for 
a long time carrying cankerworms to their young. One of 
them was noticed to take 11 cankerworms in its beak at one 
time and fly with them to the nest. The vireos, warblers, 
chickadees, cuckoos, orioles and chipping sparrows were par- 
ticularly active in catching cankerworms, and the English 
sparrow killed them in considerable numbers. 
If the thirty-six pairs of birds whose nests were found had 
succeeded in raising their young, it is probable that they 
would have disposed of most of the cankerworms in the 
neighborhood. Five thousand of these larve are sufficient to 
strip a large apple tree. One hundred and eight young would 
have been reared, had each pair of birds raised three. Ac- 
cording to Professor Aughey’s experience, 60 insects per day 
as food for each bird, both young and old, would be a very 
low estimate. Suppose each of these 108 birds had received 
its 60 insects per day, there would have been 6,480 cater- 
pillars destroyed daily. The destruction of this number of 
caterpillars would be enough to save the foliage and fruitage 
of one apple tree. In thirty days the foliage of thirty apple 
trees could have been saved, or 194,400 cankerworms de- 
stroyed. This does not include what the old birds themselves 
would have eaten. 
In these observations the influence of insect parasites and 
predaceous insects has not been entirely ignored. Hymenop- 
terous parasites were not seen to be numerous, and, as it was 
a year when cankerworms were on the increase, it is not 
probable that these parasites would have been a prime force 
in reducing the numbers of the cankerworms had the birds 
1 First Report United States Entomological Commission, 1877, p. 342. 
