476 THE INSECT WOELD. 



A small species, Hydrous fuscipes, is commoner than the large 

 one ; its body is more rounded behind. 



We are now going to consider a series of aquatic and carnivorous 

 insects ; the Dytisci, Water beetles, the Cy bisters, and iheGyrinidce, 

 or Whirligig beetles. These are perfect corsairs, whose rapacity 

 even exceeds that of many of the land Coleoptera. Not contented 

 with devouring one another, when pressed by hunger, with attack- 

 ing especially the larvae of all aquatic insects, such as the Libel- 

 lulce and Ephemera, they feed also on molluscs, on tadpoles, and 

 on small fish. It is easy to rear them in captivity. If confined 

 in a small aquarium, their habits would be much more amusing 

 than a few golden fish, which one meets with everywhere, and 



Fig. 474. Dytiscus marginalia, male and female, and front leg of male magnified. 



which are only good enough to amuse European Sckaabahams. 

 Care must be taken to cover the aquarium at the top with gauze, 

 to prevent the perfect insects from escaping. This tribe is not 

 very numerous, nor varied in its forms. An oval body, legs 

 curved and widened into oars, provided with hairs, distinguish 

 the insects which compose it. They imbibe air at the surface of 

 the water, like porpoises. 



The most carnivorous of this group are the Dytisci and the 

 Cybisters. They may be called the sharks of the insect world. 

 Nothing which lives in the water is safe against the voracity of the 

 Dytiscus. They attack small molluscs, young fish, tadpoles, larvae 

 of insects, and suck greedily the bits of raw meat which are thrown 



