AQUATIC INSECTS 



4. Hind cox£e broadly fused with the metasternum. 



Diving-beetles, Dytiscidce, p. 266 

 Hind coxas free (riffle beetles). 



Riffle-beetles, Psephenidce, p. 277 



Families of Larvae of Water Beetles 



1. Tarsal claws two. 2 

 Tarsal claws one. - 3 



2. Four hooks at each end of abdomen. GyrinidcB, p. 271 

 No hooks at each end of abdomen. Dytiscidce, p. 266 



3. Carnivorous, with conspicuous rapacious mandibles. 



HydrophilidcB, p. 273 

 Herbivorous, with short blunt mandibles. 4 



4. Legs absent — larva attached to plant by a bristle tube. 



Donacia of Chrysomelidce, p. 278 

 Legs well developed. 5 



5. Abdomen with numerous rows of dorsal spines. 



Haliplidce, p. 265 

 Abdomen with 2 rows of low tubercles or none. 



PsephenidcB, p. 277 



Crawling water-beetles, Family Haliplidae. — These are 

 small beetles (Fig. 204), one-fifth of an inch or less, which 

 crawl through the litter in every little pond; one can hardly 

 sweep the net over bottom vegetation without getting two 

 or three of them. They are oval, very convex, and their 

 general color is brown irregularly spotted with yellow. On the 

 wing-covers are rows of small punctures (Fig. 204). The 

 coxae of the hind legs are plate-like and so large that they 

 conceal the basal part of the legs. According to Dr. R. 

 Matheson who has published a study of the whole family, 

 the adults feed almost exclusively on filamentous algae, par- 

 ticularly Nitella and Chara . About forty species of Haliplidcs 

 have been found in our fauna; the species most commonly 

 seen belong to the two genera, Haliplus and Peltodytes, both 

 of which are widely distributed. 



Haliplids begin to mate in early spring and lay their eggs 



265 



