474 THE INSECT WORLD. 
-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. 474.—Pupa and larva of Dytiscus marginalis. 
waters during the greatest part of the year, but principally m 
autumn. During the winter they bury themselves in the mud and 
under moss. The females lay their eggs in the water. The 
larvee are long, swelling out at the middle, furnished with hairs, 

Fig. 475.—Dytiscus latissimus. Fig. 476.—Cybister Reselii. 
and grow rapidly. To undergo their metamorphosis into pupe, 
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. 473), of a 
