No. 4.] 



BIRDS ON THE FARM. 



125 



will not be likely to trouble bluebirds. 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 

 occupying the boxes. Two pairs of English sparrows began 

 operations, but were not allowed to proceed. 



Nestino- 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 blue- ^ 

 birds, two of which were raised, were 

 hatched in these boxes. No swal- 

 lows, martins or wrens succeeded in 

 occupying any of the boxes. The 

 experiments in this direction have 

 resulted in a partial failure, mainly 

 throuoii the abundance of the birds' 

 enemies. In respect to the chicka- 

 dee, 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 de- 

 stroys vast numbers of such orchard pests as the canker 

 worms and other soft caterpillars, taking also the hibernat- 

 ing forms of these insects, whether eggs, larvae or pupaB, in 

 gi'eat quantity. It also destroys the eggs of the forest 

 caterpillar moth (Ch'siocamjja ch'sstria) and those of the 

 common tent caterpillar (C. Americana) to some extent, 

 killing large numbers of the caterpillars of both these 

 insects, as well as those of the gypsy moth {Portlietria 

 dispar), the brown-tail moth (Eiqjivctis chrysorrhcea) and 



!iii:i!;i-im.iiil!ili!i 



Fig. 2. — SpaiTow-pi'oof Box. 



