The Food of Fishes. 68 



Food of the Adults. 



An examination of the notes on the twenty-seven adnlts 

 shows material differences of food at different parts of the 

 year. As all but one were taken from the Illinois River, 

 I have not the means of noting the correspondence of food 

 with locality. 



Five specimens taken at Peoria, in March, were fonnd 

 feeding most freely upon Cladocera, which composed fifty- 

 five per cent, of their food. These were chiefly of the two 

 species Simocephalus vetulus and S. americanus. These 

 little Entomostraca. w^ere taken at that time in such quan- 

 tity as visibly to distend the stomach when seen from the 

 outside, and the immense number of their eggs gave a red- 

 dish color to the contents of the alimentary canal. The 

 larvae of Neuroptera, both "darning-needles" and" May- 

 flies (Palingenia), were also eaten in considerable num- 

 bers (thirty-nine per cent.). A small Hybopsis, a little 

 darter {Boleosoma maculata) and an unrecognizable fish 

 were found in these stomachs, making about six per cent, 

 of the food. Only trivial numbers of Entomostraca appear 

 after this time. 



Nine specimens, taken in April, likewise at Peoria, were 

 feeding chiefly upon Neuroptera larvae (eighty-six per 

 cent.), especially upon that almost invaluable element of 

 fish food, the larvae of Palingenia hllineata (sixty-six per 

 cent. ) . A few larvae of Gyrinid* and Dytiscidae were noted 

 (three per cent.), and a few Corixas also. A Oammarxis 

 fasciatus and a little Ceratophyllum, etc., were noticed; 

 and also the flower of an elm and the feather of a bird. 



A single specimen from Pistakee Lake, in McHenry coun- 

 ty, taken in May, gave evidence of a similar reliance upon 

 Neuropterous larvse (eighty-five per cent. ). Here, however, 

 in the absence of Palingenia, Agrions and the larger dragon- 

 flies were resorted to. A little vegetation had been taken 

 with these {Ceratophyllum deniersiun and Lemna trisulca 

 ten per cent.), probably by accident, as this lake was full 

 of aquatic plants, and it would hardly have been possible 

 for a fish to catch living food from the w^ater without get- 

 ting more or less vegetation at the same time. A single 

 Hyraenopter, — the only land insect found eaten by this 



