CHAP. IX ] THE FOU11TH DA.1. 211 



head of the said carps, that the frog would not be got off 

 without extreme force or killing. And the gentleman that 



which devoured two frogs in the space of forty hours, and was found, on 

 dissection, to have digested them. It feeds greedily on spawn, and we 

 have seen one covered with it. The larva of this Dyticus, which is variously 

 called the Water- 

 devil, or Water- 

 tiger, and when 

 full grown is about 

 two inches and a 

 half long, is said 



to be even more *- */ -\ v> \- . 



destructive than S /? I 



its parent. Its 

 habit is to hang in 



the water, suspended from the surface by its tail, quite motionless, till its 

 prey is within reach, when by a sudden spring it seizes it in an instant, 

 and does not quit its hold till throughly gorged. Baker kept one in a jar, 

 which destroyed twenty tadpoles in a day, sucking them till they were 

 exhausted ; it killed a Tench three inches long in about a minute ; and 

 after some hesitation, attacked and killed a Newt four inches long. The 

 NOTONECTA, or Boat-fly, alias Water-boatman, " that topsy-turvy imp ot 

 darkness," is furnished with a lance which it strikes into its prey, and 

 speedily kills it, apparently from some poisonous property, as it acts 

 on human flesh like the sting of a wasp. The NEPA CINERBA, or Water- 

 scorpion, commonly known as the Toe-biter, will spear and kill the 

 stickleback of ten or fifteen spines, although he avoids the more formidable, 

 or perhaps less delectable species of three spines. Kirby says, that one of 

 these Water- scorpions put into a basin with three tadpoles, killed them 

 all in a very short time ; and it is known that they will kill Newts. The 

 HYDROPHILUS PICEUS, or Sleepy Beetle, (the larva of which the French call 

 the Assassin,) a very large species generally found in carp ponds, is in both 

 its states nearly as destructive as the Dyticus, although the latter, scarcely 

 half its size, will kill it and suck out its inside, leaving it apparently 

 whole. The Libellulidce are also very destructive, particularly the DRAGON- 

 FLY in its larva state. Many more of these Water-cannibals might be 

 adduced, were there space. But we cannot refrain from introducing the 

 WATER-SPIDER, which spins its filmy web at some distance from the 

 surface of ponds, and very ingeniously fixes a canopy of air about it ; this 

 animal in its turn preys, there is little doubt, on the young of the fish- 

 destroying insects, and so brings about nature's balance. There are besides 

 multitudes of fleas and minute animalculse which work the same end, by 

 infesting the larger insects. We may say with the poet : 



" Great fleas have little fleas and lesser fleas to bite 'em, 



And these fleas have smaller fleas, and so ad infinitum." 

 The curious reader will do well to pursue his own researches on these 

 subjects in works of entomology. Baker, the microscopist, was among the 

 first in this country to call attention to the havoc committed by water- 



