264 BUIX.ETIN or the bureau of fisheries. 



Distribution in the Fairport (Iowa) fishponds according to beetle families. 



Pond number and 

 series. 



Hali- 

 plidae. 



Dytis- 

 cidse. 



Gyrini- 

 dse. 



Hydro- 

 philidae. 



Total. 



Pond number and 

 series. 



Hali- 

 plidse. 



Dytis- 

 cidse. 



Gyrini- 

 dse. 



Hydro- 

 philidse. 



Total. 



12B 











17 



7D 





1 9 







28 







2 









8D 





12 





^ 



26 

 11 



14B 



2 



5 



1 



5 



13 



9D 



3 



3 



1 



4 



15B 



2 



2 



1 



5 



10 



IE 



2 



7 



1 



5 



15 

 31 



27 

 21 

 12 

 17 

 12 



16B 



2 



5 



1 



8 



16 



2E 



4 



15 



3 



9 



ID 



3 



7 



0 



5 



15 



3E 



3 



11 



3 



10 



2D 



3 



13 



3 



13 

 9 



32 



4E 



3 



10 





5 



3D 



3 



10 



9 



3 



25 

 28 



IF 



2 



3 



3 



4 



4D 



3 



4 



12 



2F 



2 



6 



3 



6 



5D 



4 



18 



3 



14 



39 

 6 



3F 



1 



4 



2 



5 



6D 



1 



0 



1 



4 



































SOURCE OF MATERIAL. 



In the summer of 1916 Geo. B. Lay collected and identified the various insect 

 forms found in the Fairport fishponds, and in 1917 Dr. R. A. Muttkowski checked 

 the species thus obtained and, with Mr. Lay, completed their identification. Both 

 made out reports of their work, containing in addition to the check list some notes 

 on the habits of certain of the insects in relation to fish breeding. The writer 

 has used their check list in its entirety as the basis of the one here presented, 

 chiefly because it was prepared during the same years that Mr. Schradieck was 

 listing the food of the fish and Dr. Emmeline Moore was studying the plant fauna 

 of the ponds. For this reason the beetle list, the plant list, and the fish-food list 

 exactly supplement one another. The first shows the kinds of beetles found in the 

 ponds from which the fish were taken, the second explains the relative abundance 

 of the beetles in the different ponds on the basis of their plant environment, and 

 the third indicates the choice the fish made of the beetles that were available. 



Every species in this beetle list has been verified by the present author during 

 the years 1918, 1919, and 1920, and to it have been added other species that either 

 escaped capture in 1916 and 1917 or have appeared more recently in the pond 

 fauna. These additions are indicated by a star (*) following the species name and 

 include only two forms that are anything more than occasional interlopers, namely, 

 Haliplus horealis and Thermonectes ornaticollis. 



INFLUENCE OF ENVIRONMENT. 



Dr. Muttkowski called attention in his report to the remarkable difference in 

 both the quantity and the quality of the population of the various ponds. This 

 is the more noteworthy because of the contiguity of the ponds. Those in the same 

 series are separated from one another by narrow banks of earth, 12 to 15 feet in 

 width, and pond 4E is separated from pond 5D by a similar narrow bank. Pond 

 6D is very small and is used as a natural aquarium in which to keep the large bass 

 to prevent them from eating other fish. They are so hungry most of the time 

 that they keep the pond cleared of all animal food throughout the siunmer. This 

 accoimts for the meagerness of its insect fauna, and it can not be fairly considered 

 in comparison with the others. Ponds 1 and 2D are contiguous, are about the 

 same size and depth, and are surrounded with the same vegetation. They were 



