BIRDS IN RELATION TO THE ALFALFA WEEVIL. 61 



The food habits of the leopard frog stamp it as one of the most 

 beneficial of the lower vertebrates. Its only harm lies in the destruc- 

 tion of beneficial predaceous and parasitic insects, but this is out- 

 weighed by its persistent attack upon such insect pests as mosquitoes, 

 crickets, grasshoppers, and the predaceous water beetles injurious to 

 small fish fry. It is deplorable that so many of these batrachians 

 are being slaughtered, either for fish bait or for the small morsel of 

 food which their legs afford. 



CONCLUSION. 



The investigation of the food habits of the birds of Utah in rela- 

 tion to the alfalfa weevil verifies the statement frequently made that 

 the abundance of an insect, and consequently the ease with which it 

 may be secured, are important factors governing the food habits of 

 birds. With the exception of a few restrictions placed upon certain 

 species by their methods of feeding, insectivorous birds are to a 

 certain degree indiscriminate in their choice of food. Flycatchers, 

 swallows, nighthawks, etc., are limited in a large measure to flying 

 insects; thrushes, meadpwlarks, blackbirds, and gallinaceous species 

 secure most of their insect food from the ground; while warblers, 

 chickadees, woodpeckers, cuckoos, etc., feed largely among the tree 

 tops. It is the ground-feeding birds which come into most intimate 

 contact with the alfalfa weevil, but birds that feed on the wing may 

 secure the insect at the time of its spring and summer flights; and 

 such species as search for their food over trunks of trees may come 

 into contact with a few hibernating adults. Over much of the terri- 

 tory covered by the writer in his two seasons' work these bird enemies 

 of the weevil had learned to search for the insect as a food in the 

 comparatively short period of four or five years, a fact which makes 

 the large proportion of this food eaten by some species the more 

 remarkable. 



With the possible exception of a fungous disease, which in some 

 localities destroyed large numbers of the pupae, there probably was, 

 at the close of 1912, no other natural agency which had done more in 

 holding the alfalfa weevil in check than the native birds. Being 

 alert to detect any unusual abundance of suitable food in the insect 

 world, they were among the first to turn their attention to this new 

 pest, and when once a convenient supply of this food was found in 

 the alfalfa these fields became popular with many species. It is 

 quite possible that in the case of some of the birds examined a knowl- 

 edge of the location of this insect had been only recently acquired, 

 and a few years more experience with it would place these species 

 much higher in the scale of weevil enemies. 



