220 



PEESH-WATEE AQ0AEIA. 



The larvse, although their parents are almost entirely 

 herbivorous, are carnivorous. They are great eaters and quick 

 growers ; and they are not so long in the larval state as are 

 the larvse of the Dytisci, but are ready to become pupae 

 within a few weeks from the time they are hatched, if they 

 have been able to obtain a sufficiency of suitable food. The 



Fig. 110. Hydbophilus piceus. a. Full-grown Larva ; b. Egg-sac, affixed to 

 Aquatic Plant ; c, Egg-sac opened, showing Eggs ; d. Young Larvse ; 

 e, e, Mature Insects ; /, Leaf of Aquatic Plant. 



larvse of B. piceus are very difficult indeed to rear from 

 the egg while in captivity. The only chance of doing so is 

 to provide them with a great quantity of small aquatic animal 

 life, and especially the fry of water-snails. These larvse, 

 when well fed and full grown (a. Fig. 140), are longer and 

 thicker than are those of D. marginalis under similar circum- 

 stances. They have the power of moving the head, apparently 

 with great ease, in every direction, and as they feed upon 



