58 INSECTS AT HOIVIE. 



is sure to take to its wings and fly off in search of more food. 

 Even gold fish have been attacked by this insatiate devourer, 

 which does not even spare its own kind, and devours the oppo- 

 site sex as well as its own. When these Beetles take flight 

 from the pond or stream in which they have been living, they 

 always crawl up a reed or a water-plant, so as to gain space to 

 spread their beautiful wings. In consequence of this freedom 

 of locomotion, this Beetle may be found in almost any pond, 

 however small it may be. Even when ponds have been reduced 

 to mere puddles by the drought of summer, the Dyticus may 

 be found plentifully, hiding itself in the still soft mud. 



The mode in which this insect breathes is really wonderful. 

 Being an insect, it is forced to breathe atmospheric air, and 

 yet it has to pass the greater part of its time under water. 

 The problem is solved by the Beetle converting itself for the 

 nonce into a diving bell, receiving the supply of air as often as 

 needful. This feat is accomplished in the following way : — The 

 body is rather flat, so that there is a space between the folded 

 wings and the elytra. Now, these elytra are very large, and, 

 when closed, are quite air-tight. When the Beetle wishes to 

 breathe, it comes to the surface of the water with its head 

 downwards, and just exposes the tip of its abdomen to the air. 

 In a moment it has expelled the air which has already been 

 used in breathing, and taken in a fresh supply, with which it 

 dives to the bottom. As the spiracles, or mouths of the breath- 

 ing tubes, open into the space between the elytra and the 

 abdomen, they can take in the air, and pass it through the 

 system. Sometimes, if the observer will approach very quietly, 

 he may see the Beetles floating with tlieir heads downwards, 

 the tips of their tails just above the surface of the water, and 

 their hind legs spread out so as to balance the body in this 

 .-strange position. All the Dyticida3 employ this curious mode 

 ..of supplying themselves with air, but it is most conspicuous in 

 ■tibe larger species, and is therefore described in connection 

 ^^.vith this Beetle. 



There is a rather remarkable point in the structure of the 



irwings. On the inside of the elytra, and at their bases, is a 



pair of membranous plates with finely-fringed edges, something 



like wings, for which reason they have been called ' alulets,' or 



I iittle.wings. These cannot be seen while the insect is at rest, 



