48 NEW YORK STATE MUSEUM 



the forests. The service rendered by insectivorous species in destroying 

 centers of infection is especially to be emphasized in connection with the 

 benefit the birds render by destroying insects ; while in the case of arboreal 

 species it is immediately evident that we are practically dependent upon 

 the birds for preserving our forests and taller shade trees, because spraying 

 operations in these cases are practically out of our control, and the only 

 means of preserving us from undue increase of the defoliating insect is, 

 besides weather conditions, the work of parasites and the voracious appetite 

 of our insectivorous birds. Some birds are especially fond of plant lice. 

 In this number we might include the wood warblers and kinglets, which, 

 while loitering with us on their annual migration, attack the female plant 

 lice which have survived the winter and are about to produce countless 

 progeny of leaf -sucking descendants. I have watched them on many 

 occasions and counted from fifteen to seventy-five a minute swallowed by 

 each warbler observed. Some are even fond of hairy caterpillars. This 

 number, unfortunately, is very small but includes the cuckoos and, to 

 a certain extent, the orioles and waxwings. Others prefer the white 

 ground grub. Here should be mentioned the Robin, Grackle and Crow, 

 which do considerable damage in other respects but atone in this manner 

 for many of their sins. Woodpeckers seek the boring larvae of various 

 beetles and moths found beneath the bark and in winter destroy numerous 

 cocoons which are hidden in the crevices of the bark and dead limbs. 

 Thus, if the whole list of birds is examined, we shall find that nearly every 

 kind of insect which is conspicuous as a destructive species will have 

 some bird enemy which seems to prefer it as diet; and if the balance of 

 nature had not been so ruthlessly disturbed by mankind the plagues of 

 locusts, plant lice, army worms and elm tree beetles would be cured in 

 the natural process of adaptation. 



Destruction of weed seeds. In all cultivated fields there are found 

 many species of plants popularly known as weeds which often seem more 

 adapted to occupying the soil successfully than the crops which the farmer 

 wishes to raise. These weeds must be destroyed or held in check by some 



