WATER BEETLES IN RELATION TO PONDFISH CULTURE, 

 WITH LIFE HISTORIES OF THOSE FOUND IN FISHPONDS 

 AT FAIRPORT, IOWA. 



By CHARLES BRANCH WILSON, Ph. D. 

 State Normal School, Department of Science, Westfield, Mass. 



Contribution from the U. S. Fisheries Biological Station, Fairport, Iowa. 



CONTENTS. 



Page. 



Introduction 232 



Importance of water beetles 232 



Ignorance of American species 232 



Lakes versus fishponds 233 



Methods 233 



Ecology 235 



Modifications of structure and vestiture . 235 



Locomotion 235 



Migration from one pond to another 237 



Distribution according to size 238 



Structural adaptations 238 



For locomotion 238 



For respiration 239 



For flotation 241 



For sex functions 242 



For sight 242 



Enemies of larvae 242 



The larva 242 



Time of pupation 243 



Dragonfly nymphs 243 



Mites 244 



Hydra 244 



Ants 244 



Turtles 244 



Frogs 244 



Snails 245 



Parasites 245 



Enemies of pupse 245 



Water 245 



Imperfect pupation 246 



Parasites 246 



The black horsefly 246 



Ants 247 



Page. 



Enemies of adults 247 



Turtles 247 



Birds 247 



Toads and frogs 248 



Electric lights 248 



Beetles as fish eaters 249 



Fish as beetle eaters 252 



Evidence from fish bait 252 



Evidence from fish stomachs 253 



General summary and suggestions 260 



Beetle distribution in Fairport fishponds 263 



Source of material 264 



Influence of environment 264 



Restriction of species 266 



Relative importance of species 267 



Systematic description of Fairport species. . . 267 



Key for identification of larvae 268 



Key for identification of pupae 269 



Peltodytes 271 



P. edentulus 271 



Haliplus 273 



H. ruficollis 274 



Coptotomus 275 



C. interrogatus 275 



Cybister 277 



C. fimbriolatus 277 



Dytiscus 282 



D. verticalis 282 



Hydroporus 285 



H. niger.. 285 



Laccophilus 286 



L. maculosus 286 



L. proximus 290 



231 



