AQUATIC CARNIVOROUS BEETLES j DYTICUS. 123 



considerable proportion are found in Britain and other temper- 

 ate countries; but the largest and most brightly-coloured species 

 are confined to warmer climates. 



703. The aquatic Carnivora, or HYDRADEPHAGA, form a 

 tribe far less numerous than the terrestrial species - r and are at 

 once distinguished by the peculiar modification of the legs, 

 which adapts them for swimming, these members being flat- 

 tened, and fringed with bristles, so as to serve as oars. They 

 live, during their larva and perfect states, in water ; but they 

 quit that element to undergo their metamorphoses, and to pass 

 the time of their pupa condition. The larvae have the body long 

 and narrow, with a strong head armed with powerful mandibles ; 

 and they are of very active carnivorous habits. Both the larva? 

 and the perfect insects can only breathe air, and are obliged to 

 come to the surface occasionally for that purpose. The Dyticus, 



the principal genus 

 of this tribe, is com- 

 mon in fresh and 

 placid waters, such 

 as lakes, pools, or 

 ditches. Its larva 

 feeds upon other 

 aquatic larvas, such 

 as those of dragon - 



FIG. 439. DYTICUS MARGINALIS AND LARVA. n> 



flies, gnats, &c. ; 



and moves quickly through the water, by means of strokes with 

 its expanded tail. The pupae may be found buried in the 

 adjoining banks. The imago also is very voracious, feeding 

 principally upon the juices of the animals it attacks, which are 

 often much larger than itself; an individual has been kept in a 

 large bottle of water for three years and a half, being fed once 

 a week or oftener with a bit of raw beef. 



704. The GYRONECIIINA, or Whirligigs, as they are com- 

 monly called from their peculiar movements, are placed with the 

 aquatic Carnivora by many authors. In these the second pair 

 of maxillary palpi does not exist ; and the antennae, instead of 

 being slender and filiform, are short and clubbed. The com- 



