WATER BEETLES IN RELATION TO PONDFISH CULTURE. 257 



Food of Louisiana fish, by H. E. Schradieck. 



(Figures in the last five columns are percentages, the total food being 100.] 



Kind of fish. 



Num- 

 ber 



^^ex-^ 

 amined. 



Ex- 

 tremes 



in 

 length 

 of fish, 



milli- 

 meters. 



Num- 

 ber 



of fish 

 contain- 

 ing 



beetle 

 food. 



Length 

 in miUi- 

 meters 

 of fish 

 contain- 

 ing 

 beetle 

 food. 



Terres- 



beetles, 

 adults. 



Hydro- 

 phiUd 

 beetles 

 adults. 



Hgdro- 

 beetles 



Dytis- 



cid 

 beetles, 

 adults. 



HaU- 



plid 

 beetles, 

 adults. 



Ch8enobr3^tus gulosus, warmouth bass 



16 



25 115 



1 

 2 



45 

 103 

 13 

 41 

 50 

 50 

 50 

 54 

 60 

 60 

 60 

 70 

 38 

 90 

 90 

 92 

 85 

 94 

 100 

 100 

 110 

 60 

 70 





65 

 50 









Gambusia, aflBnis, viviparous top minnow 











oo 



ZD, <0 



- - - 



86 













25 







Lepomis megalotis, long-eared sunfish 





10 











10 













40 

























10 















zU 































17 



50, 100 





30 





30 



Lepomis miniatus, scarlet sunfish 





10 

 15 

 10 





























14 



70, 120 







io 





Lepomis symmetricus, symmetrical sunfish 





10 

 10 

 20 

 25 

 10 











































1 



32 



60 

 45,70 











Pomoxis sparoides, calico bass 









8 













The data for this table of the food of Louisiana fish were taken from manuscript 

 notes by H. E. Schradieck on file in the office at the U. S. Fisheries Biological 

 Laboratory at Fairport, Iowa. 



None of these fish that ate beetle food were under 40 mm, in length, with 

 the exception of the single top minnow and one long-eared sunfish. The former 

 is easily accounted for by the fact that it feeds at the surface, and the beetles it 

 had eaten were land species that had fallen into the water and were floating on the 

 surface. The sunfish were so near 40 mm. in length that it does not constitute a 

 real exception. 



The adult hydrophilid beetles furnished the most attractive food, probably 

 because they were more numerous in the localities from which the fish were obtained. 

 If we include the larvae with the adults, the Hydrophilidse served as food for 16 

 out of the 23 fish that ate beetles, or more than 75 per cent. In the next table, 

 the data for which were taken also from manuscript notes by H. E. Schradieck on 

 file in the ofiice of the U. S. Fisheries Biological Laboratory at Fairport, Iowa, this 

 order is reversed and the Dytiscidae have twice the percentage of the Hydrophilidae. 



