COLEOPTEKA. 



477 



to them. They may be kept in an aquarium for many years, by 

 feeding them on animal matter. Their oval-shaped body, with its 

 sharp sides, permits them to cut through the water with great ease 

 the hind legs serving as oars. They are to be found in stagnant 



Fig. 415. Pupa and, larva of Dytiscus marginalia. 



waters, during the greatest part of the year, but principally in 

 autumn. During the winter they bury themselves in the mud and 

 under moss. The females lay their eggs in the water. The 

 larvse are long, swelling out at the middle, furnished with hairs, 



Fig. 476. Dytiscus latissimus. 



Fig. 477. Cybister Kceselii. 



and grow rapidly. To undergo their metamorphosis into pupae, 

 they bury themselves in the earth. 



The perfect insects are amphibious, and fly from one pond to 

 another to satisfy their voracious appetites. The most common 

 species of this genus is the Dytiscus marginalis (Fig. 474), of a 



