78 THE HYDRADEPHAGA, 



given above, is a stout, portly-looking insect, the 

 moderate convexity of his back reminding one of the 

 gentle swell observable in the waistcoat of a well-to-do 

 middle-aged gentleman who has discovered the sum- 

 mum honum of human existence to consist in a good 

 dinner; but the larva, although his actions would 

 seem to indicate his adoption of this view of affairs, 

 certainly does very little credit to his good living. On 

 the contrary, he is a slender, wriggling worm, with 

 a most villanously hungry aspect, thickest about the 

 middle, and tapering off nearly to a point at the tail, 

 and his head is armed with a pair of long sickle- 

 shaped jaws of a most formidable appearance. The 

 upper surface of the segments, especially the anterior 

 ones, is horny ; the three first segments of the body 

 are furnished with jointed legs; and the general 

 colour of the creature is a pale dingy brown. The 

 structure of the mandibles is peculiar ; they are acute 

 and hollow, and exhibit a small slit close to the tip. 

 The larva, on capturing his prey, which consists prin- 

 cipally of other aquatic larvse, buries his formidable 

 jaws in their bodies, and thus sucks out their juices 

 with very little trouble. 



Like the perfect insect, the larva of Dyticus is com- 

 pelled to rise occasionally to the surface of the water 

 to breathe, and in both respiration is effected by 

 bringing the extremity of the tail to the surface of 

 the water. In the larva the only effective stigmata 

 are situated at this part of the body, and protected by 

 a pair of narrow appendages fringed with hairs, which 

 assist in the suspension of the insect at the surface, 

 and prevent the ingress of water during the process 

 of respiration. 



When full grown the larva of Dyticus marginalis is 



