20 Searle, The Pond and its Inhabitants. [voT."^xxxi 



ramify the body of the larvcu. The mature larvae leave the 

 water, and, burrowing into the bank of the pond, make a cocoon- 

 like cell in which to pupate, and from which they finally emerge 

 as perfect beetles. 



Another water-beetle, Cybister,* is also a common inhabitant 

 of our ponds, and its larvae, which are erroneously called 

 Dytiscus larvae, is perhaps the most bloodthirsty marauder 

 in the pond, and seems to kill for the love of killing. It is 

 absolutely devoid of fear, and will attack any living creature 

 in the pond that comes near it. One afternoon at Cheltenham 

 I saw one of these larvae, and a half-grown one at that, attack 

 and kill in rapid succession three large tad])oles. Like the 

 larvae of their relative. Dytiscus. which they closely lesemble. 

 they possess a pair of enormous sickle-shaped jaws, which 

 they drive into their victims. These jaws are hollow for about 

 two-thirds their length from the base, the remaining third 

 being the solid point. Just at the base of the solid point, 

 the inner side of the cur\'e, there is a small opening which leads 

 into the hollow part of the jaw, and through these the blood 

 and body juices of the victim is sucked. At one time it was 

 thought tliat this was the only opening into the alimentary 

 canal, and that the larva did not possess a mouth : but it really 

 has a very large and peculiarly-shaped mouth, which closes 

 so tightly that it is difficult to see, but is readily made apparent 

 if the head is subjected to lateral pressure. It is stated by 

 some writers that Dytiscus inject a poison into their victims 

 which causes them to liquefy. I do not know whether Cybister 

 ib possessed of such a means of offence, but, from the rapidity 

 with which their victims die after being bitten by the larvit;, 

 one would tliink they did ; this is a point that needs investiga- 

 tion. 



Beetles, though they dive and swim freely in the water, 

 breathe air, and must come to the surface at intervals to renew 

 their supply. Some imprison this air sui)ply between the 

 elytra and the abdomen, and as the spiracles, or oi)enings to the 

 breathing tubes, arc placed along the back of the abdomen, are 

 able to breathe this air while they are under water. Others, 

 in addition to this, take a further supply of air entangled among 

 the hairs on the under-side of the body, and as the beetle darts 

 aliout in the water these air bells shine like burnished silver. 



Another insect whose whole life is spent in destroying its 

 weaker fellows is the drag(jn-tly. The female insect lays her 

 eggs just below the surface of the water on the leaves and 

 stems of water-plants. When newly hatched, the young laryae 

 appear to be all legs and a pair of eyes, and creep about on 



* This beetle is now called Homceodytcs scutellaris. 



