432 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



sparrow and declares that the cities owe their freedom from this insect to 

 that bird."* 



Cankerwoims, also of the family Geometridse, are a treat for most 

 birds, and in special investigations of outbreaks it has been found 

 that practically all birds of the infested region were feeding freely 

 upon them. This has resulted in noticeable control, recorded in two 

 cases, and in local suppression in live. 



Canker worms, as well as many of the other larvae heretofore con- 

 sidered, are well exposed to birds and other enemies, but caterpillars 

 that are concealed by no means escape, for example, larvae of the 

 leopard moth, which are very destructive to shade trees, but which 

 in various localities have been noted to be held in check by native 

 birds. " No other explanation," says Dr. W. E. Britton, " can be 

 given of the scarcity of the leopard moth in the country, adjacent 

 to infested towns, except the presence of insectivorous birds. 

 * * * Mr. James Walker, of Newark, N. J., states ' that infested 

 elms placed in a nursery outside of the city limits of Newark were 

 rid of the larvae by woodpeckers.' " ^^ 



Among the Tortricidae the codling moth is the greatest pest, and 

 almost every entomologist who has written on the subject substan- 

 tially agrees with Prof. M. V. Slingerland that " by far the most 

 effective aids to man in controlling the codling moth are the birds." ^- 

 The two facts that have chiefly led to this conclusion are the great 

 scarcity of intact hibernating cocoons and the abundance of empty 

 ones which have evidently been rilled by birds. Long ago Messrs. 

 Benjamin D. Walsh and C. V. Riley, noted entomological collabo- 

 rators, said :^^ 



From the careful inspection of several large orchards in the early spring 

 months, we are convinced that almost all of the cocoons of the apple-worm 

 moth that have been constructed in the autumn on the trunks and limbs of 

 apple trees are gutted of their living tenants by hungry birds long before the 

 spring opens. 



In Virginia, according to Mr. J. E. Buck, " counts of over 400 

 cocoons observed on apple trees revealed the fact that * * * 

 birds had destroyed fully 85 per cent of the worms." ^* 



From New Hampshire comes this report by Dr. E. D. Sanderson : ^^ 



Only 5 to 20 per cent of the larvae survived the winter. An examination of 

 seven trees, which averaged over 38 cocoons per tree in the fall, showed but 

 5 per cent alive in the spring, 87 per cent having been killed by birds, 4 per 

 cent by disease, and 3 per cent by cold. In another orchard 1,096 cocoons 



""Cornell Univ. Exp. Sta. Bull. 1!8G, p. G2, 1010. 

 81 Ann. Uep. Conn. Agr. Kxp. Sta. 1911, p. 329. 

 "Bull. 142, Cornell Agr. Exp. Sta., p. 41, 1898. 

 ^"American Entomology, I, p. 11,3, 1.SC9. 

 3* .Ann. Rep. Va. Exp. Sta., p. 5"., 1908. 

 "^Agr. Exp. Sta. Bull. 143, pp. C4 and 82, 1909. 



