16 



FIG. 2. Sparrow-proof 

 Box. 



cult for the sparrows to drive the wrens away. The hole 

 always should be small enough to keep out blue jays, gray 

 squirrels and owls. The openings to the 

 boxes put up in 1901 were too large, and, 

 although many birds came to them, they 

 were so annoyed by their many enemies 

 that only one pair of bluebirds succeeded 

 in raising a brood, no other birds occupy- 

 ing the boxes. Two pairs of English spar- 

 rows began operations, but were not allowed 

 to proceed. 



Nesting materials were scattered about 

 and hung from the branches of the trees, 

 so that bluebirds, wrens and swallows might 

 have unlimited material at hand. This 

 was continued in the spring of 1902, but 

 only three broods of bluebirds, two of which were raised, 

 were hatched in these boxes. No swallows, martins or 

 wrens succeeded in occupying any of the boxes. The experi- 

 ments in this direction have resulted in a partial failure, 

 mainly through the abundance of the birds' enemies. In 

 respect to the chickadee, however, this experiment has given 

 results which will compensate in a large measure for its failure 

 in other directions. Studies of the food of the chickadee have 

 convinced me that it is perhaps the most useful of all birds in 

 the orchard, and as valuable as any in the forest or woodland. 

 This bird destroys vast numbers of such orchard pests as the 

 cankerworms and other soft caterpillars, taking also the hiber- 

 nating forms of these insects, whether eggs, larvae or pupse, in 

 great quantity. It also destroys the eggs of the forest cater- 

 pillar moth and those of the common tent caterpillar to some 

 extent, killing large numbers of the caterpillars of both these 

 insects, as well as those of the gypsy moth, the brown-tail moth 

 and other hairy caterpillars. It is a great feeder on the plant 

 lice, and the bark beetles are also eaten by it. These insect 

 families contain some of our worst tree pests. Chickadees are 

 continually searching over the bark of the trunks, limbs and 

 twigs of trees. In this occupation they find and destroy the 

 eggs of moths and plant lice, the cocoons of the codling moths, 



