COLEOPTERA. 



475 



in such a manner that the animal seems to be clothed in pearls. It 

 is thus the air reaches the spiracles. The female of the Hydrophilus 

 is sometimes seen clinging to aquatic plants, head downwards, 

 forming her cocoon, terminated by a long pedicle, in which she 

 places her eggs, by means of the two bristles situated at the 

 extremity of the abdomen (Fig. 472). After having drawn this 

 after her for some time, she leaves it to itself in calm water. At 

 the end of a fortnight, there come out from it little brown larvae, 

 very active, which ascend the water plants. These larva) are at 

 the same time herbivorous and carnivorous. They live on plants 

 and small molluscs, which they seize from underneath, and whose 

 shell they break by pressing them against their back, to extract 



Fig. 472. Bristles at the extremity of the 

 abdomen of the Hydrophilus. 



Fig. 473. Pupa of the Hydrophilus. 



from it the animal. If attacked, they emit a black liquid, which 

 discolours the water, and enables them to escape. At the end of 

 two months, the larva comes out of the water, and burrows into 

 the ground to undergo its metamorphosis into a pupa (Fig. 473), 

 which becomes a perfect insect a month afterwards. The latter 

 gets its colour little by little, and comes out of the ground at the 

 end of twelve days. According to M. Dumeril, the intestine of 

 the larva grows gradually longer and longer, as its diet becomes 

 that of herbs, the adult preferring vegetable food to animal 

 matter. It is at the end of summer that the Hydrophilus piceus 

 becomes perfect, and it passes the winter in a state of torpor at 

 the bottom of the water. The females lay in the month of April. 



