GREAT BROWN WATER BEETLE 259 



largest members of the British Coleoptera, and is 

 a great favourite among those possessing an 

 aquarium. The young naturalist, however, must 

 be careful, for Dytiscus Marginalis is a cannibal^ 

 and has distinct carnivorous habits. It has, in 

 fact, been aptly termed the Crocodile of insect 

 life. It preys upon almost everything within 

 reach of its powerful mandibles, and strikes 

 terror wherever it chooses to roam. It is well 

 protected in its armour of olive-brown mail^ 

 bordered with yellow; it swims and dives with 

 amazing swiftness, and carries down with it into 

 the limpid depths a supply of air beneath the 

 wing covers. Then, when the supply is ex- 

 hausted, it rises to the surface and breathes again. 

 Perchance the insect will dive once more and 

 pursue another unwary victim, or, it may suddenly 

 decide to go on a foraging expedition and explore 

 another sheet of water some little distance away. 



This species resorts to stagnant water, and 

 when it flies from one pond to another it carries 

 upon its body on occasions the seeds and eggs of 

 various aquatic plants and animals, and thus aids 

 in their distribution. The flattened posterior legs 

 are long, and are fringed with hairs, and by this 

 means the Beetle is able to use them as a pair of 

 strong oars. 



The larva of this insect is a somewhat gruesome- 

 looking creature. It has a strong, fleshy body, 



