THE ROLE of vertebrates IN THE CONTROL OF 



INSECT PESTS 



By W. L. McAtee 



Assistant in charge. Division of Food Habits Research, 



United states Biological Survey. 



[With 7 plates] 



That vertebrates eat insects is common knowledge. What their 

 destruction of these creatures means to the welfare of man, however, 

 is appreciated by comparatively few. Indeed, even at this late date, 

 it must be confessed that we know so little about the food habits of 

 vertebrates other than birds that it is impossible to give a very 

 satisfactory account of them. The unavoidable result of this situa- 

 tion is that the present paper while technically embracing all of the 

 vertebrates, practically is devoted very largely to birds. 



However, to give other members of the backboned clan their due, 

 we may begin by adverting to a fact made familiar by the worlc of 

 the Bureau of Fisheries, as well as by that of the Bureau of 

 Entomology, that certain small fishes are effective enemies of mos- 

 quito larva^, and that they can be used to advantage by man in his 

 warfare against these pests. This seems to be the only outstanding 

 credit to the fishes, although trout, and no doubt other fishes in 

 infested Avaters, devour many black-fly larvae. The feeding of fishes 

 on land insects dropping into the water is of little economic sig- 

 nificance, because desultory, and affecting individual insects, a large 

 proportion of which would be eliminated anyway by drowning. 



Among the class that is ranged next to the fishes — namely, the 

 amphibians — we have numerous insectivorous forms, but because of 

 iheir aquatic habitat many of them come but little in contact with 

 insects injurious to man. The toads constitute a striking exception 

 to this rule, especially the common forms that frequent cultivated 

 fields and gardens. Toads are practically omnivorous in relation to 

 invertebrates occurring in their habitat, and if an insect living on or 

 near the ground is abundant enough to be the cause of damage we 

 may be sure that any toads in the area will be feeding upon it. The 

 common toad has a good record as a predator upon miliipeds, ants, 



415 



