INSECTS IN RELATION TO OTHER ANIMALS 239 



fish, and the shovel fish, seventy species out of the eighty-seven which 

 I have studied. 



" Among the above, I found them the most important food of the 

 white bass, the toothed herring, the shovel fish (fifty-one per cent.), and 

 the croppies; while they made a fourth or more of the alimentary con- 

 tents of the sheepshead (forty-six per cent.), the darters, the pirate 

 perch, the common sunfishes (Lepomis and Chcenobryttus) , the rock 

 bass, the little pickerel, and the common sucker (thirty-six per 

 cent.). 



"Ephemerid larvae were eaten by two hundred and thirteen Speci- 

 mens of forty-eight species not counting young. The larva of Hexa- 

 genia, one of the commonest of the 'river flies,' was by far the most 

 important insect of this group, this alone amounting to about half of 

 all the Neuroptera eaten. It made nearly one half of the food of the 

 shovel fish, more than one tenth that of the sunfishes, and the princi- 

 pal food resource of half-grown sheepshead; but was rarely taken by 

 the sucker family, and made only five per cent, of the food of the catfish 

 group. 



"The various larvae of the dragon flies, on the other hand, were much 

 less frequently encountered. They seemed to be most abundant in 

 the food of the grass pickerel (twenty-five per cent.) and next to that, 

 in the croppie, the pirate perch, and the common perch (ten to thirteen 

 per cent.) . 



" Case-worms (Phryganeidae) were somewhat rarely found, rising to 

 fifteen per cent, in the rock bass and twelve per cent, in the minnows of 

 the Hybopsis group, but otherwise averaging from one to six per cent, 

 in less than half of the species." 



Insects in Relation to Birds. From an economic point of view the 

 relations between birds and insects are extremely important, and from 

 a purely scientific standpoint they are no less important, involving as 

 they do biological interactions of remarkable complexity. 



The prevalent popular opinion that birds in general are of inesti- 

 mable value as destroyers of noxious insects is a correct one, as Dr. 

 Forbes proved, from his precise and extensive studies upon the food of 

 Illinois birds, involving a laborious and difficult examination of the 

 stomach contents of many hundred specimens. All that follows is 

 taken from Forbes, when no other author's name is mentioned, and 

 though the percentages given by him apply to particular years and would 

 undoubtedly vary more or less from year to year, they are here for con- 

 venience regarded as representative of any year and are spoken of in 



