KYDROPIJILID^. 



437 



are liatched in about eight days. They are myriapodous in 

 form, with a pair of large, long, lateral respiratory filaments 

 on each segment, much as in the larva of 

 Corydalus. Tliey become fully grown in Au- 

 gust, crawl out of the water and spin an oval 

 cocoon, within which the pupa remains a 

 month, and then appears as a beetle. In Gy- 

 rinus (Fig. 380, G. borealis Aube ; Fig. 381, 

 larva of a P:uropean species) the scntellum is 

 distinct; the species of Diiieutus, of which D.Ameri- 

 canus is a type, are larger, and lack the scntellum. 

 Fig. 381. Schiodte states that the larvie of Carabichf^, 

 Dytiscidoi and Gyrinidce difier from those of other Coleop- 

 tera in having double claws, while in the others the tarsus is 

 undivided and claw-like. 



FiK. ;j80. 



IIydrophilid^ Leach, Carnivorous as larv.T, but when 

 beetles, vegetable eaters, and living on refuse and decaying 

 matter, this family unites the habits of the foregoing families 

 with those of the scavenger Silphids, They are aquatic, small, 

 convex, oval, or hemispherical beetles, in which the middle and 

 posterior feet are sometimes adapted for 

 swimming ; the antenna are short, and the 

 palpi very long and slender. The females 

 spin a silken, turnip-shaped nidus for their 

 eggs, fifty to sixty in number, which ends 

 in a horny projection, serving as a respira- 

 tory tube to supply the young larva? with 

 air as they are hatched. Others carry the 

 cocoon about with them on the under side 

 of the body. To spin this large amount of 

 silk, they ai-e provided with two large silk 

 glands, with external spinnerets. The larvi^ 

 hatch in from two to six weeks, and moult 

 three times ; when mature the}' are long, c}-- 

 lindrical, tapering rapidly towards the pos- 

 terior end, with short legs, while the head is 

 flattened above and very convex beneath, with the mandibles 

 elevated much as in the larva of Cicindela, enabling them to 



382. 



