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. 
& 
CONT 
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 1 243 
Dragonfly nymphs 243 
Mites 244 
Hydra 244 
Ants 244 
Turtles 244 
Frogs 244 
Snails 245 
Parasites 245 
Enemies of pupae 245 
Water 245 
Imperfect pupation 246 
Parasites 246 
The black horsefly 246 
Ants 247 
ENTS. 
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 pupse 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 
