no 



the utmost rapidity, suddenly throwing out their forceps, and seizing them with as much 

 eagerness as a pike does the unwary gudgeon ; they then bring their forceps up to their 

 mouth with their prey in it, and feast on their captive prisoner. Nor is their voracious 

 nature less astonishing ; and the greediness with which the large ones seize other small 

 animals would hardly gain belief among persons entirely ig-norant of this study. I have 

 seen one of them, in less than an hour's space, devour three uasects, each of which was full 

 two thirds as big as itself ; but, in general, the small ones are the sacrifices made by the 

 o-reater ; wherein I must observe, that when they have got a caterpillar of the small 

 Libellas in their forceps, such as those of Fig. 1. Plate 47., they leave no part uneaten, 

 except the three tails, which they let fall to the bottom, as perhaps not having substance 

 in them sufficient to afford them proper nourishment ; for as their food consists altogether 

 of animals less than themselves, they neither spare the caterpillars of the lesser Libellse, 

 nor confine themselves to those belonging to other tribes. They will eagerly prey upon 

 the dififerent kinds of Cads, or caterpillars of the Phryganese ; great numbers of whom, at 

 certain seasons, quit those husks or cases they make and swam about, with less fear and 

 dread than in the earlv part of the spring. I have also seen the caterpillars of the Nota- 

 necta's or Boat-flies devoured by them, and not seldom the small blood-worms, as they are 

 called. In short, there are but few of the lesser animals that live in the water, but when 

 once they get within the reach of their instruments will certainly fall \'ictims to these fresh- 

 water Leviathans. 



" I could never observe that these caterpillars ever threw off any exuvia, or skin, in 

 their progress from the egg to the complete animal, as most other insects do that live in the 

 open air ; neither could I ever perceive any difference between the caterpillars and chry- 

 salis's of this genus in their outward forms * : the same voracious behaviour in seizing and 

 devouring their prey, reigning both in one and the other ; but that they internally undergo 

 some material alteration, when passing their respective states, is what I do not entertain 

 the least doubt of ; as the organs of respiration during the creature's life in the water, 

 appear to me to be under a necessitv of recei\-ing a great alteration, when they are to 

 perform the same office in so different a medium as the air ; nor can I suppose this busi- 

 ness to be done in so quick and sudden a manner, as the short space of time in which the 

 creature would then be passing from the caterpillar state to the perfect one would permit, 

 mthout having the intestines prepared, as it were, and fitted by some previous change. 

 However, as this is conjecture only, I shall dwell no longer on this head, my present pur- 

 pose being to point out and describe their general circumstances and beha\aour. 



" When the caterpillars of the respective species have arrived to their full growth, and 

 nature inforais them they are to quit their fonner element of water, for one wherein they 

 are to appear invested with very different powers, they prepare for this extraordinary 

 change ; and, creeping up the sticks, straws, or plants they find for their purpose, whose 

 tops grow out of the water, they entirely quit that element, and, stopping at about six or 



• The presence of the dorsal whig cases indicates tlie arrival of the insect at the pupa state. 



