328 



DRAGON-FLY. 



commonly seen about water. Often two of these 

 insects may be observed flying together in a line, the 

 neck of the hinder one, which is the female, being 

 held by the extremity of the tail of the one in front, 

 or the male. 



Shortly after this has been seen, in walking on the 

 banks of water, a rustling sound may be heard amongst 

 the aquatic plants growing thickly together, and which 

 is soon discovered to be caused by the wings of the 

 female touching the stems of these plants whilst in 

 the act of depositing her eggs on the water. During 

 this act the tail is beat upon the surface of the water 

 with rapid succession, until the eggs form a mass 

 somewhat like a bunch of grapes. 



The larvae are soon hatched, and the insect retains 

 its aquatic habits until the moment when it assumes 

 the winged state. So long as they remain in the 

 water, they change their form but slightly, but 

 retain nearly that which they exhibit at their first 

 exclusion from the egg. Old Izaak Walton tells 

 us a marvellous story about a green caterpillar or 

 worm, as big as a peascod, " which I have seen, and 

 may therefore affirm it to be true," found upon a 

 privet hedge, and which was kept in a box, and fed 

 with privet, " but by some neglect in the keeper of 

 it, it then died, and did not turn to a fly ; but, if it 

 had lived, it had doubtless turned to one of those flies 

 that some call flies of prey, which those that walk by 

 the rivers may in summer see fasten on smaller flies, 

 and I think make them their food." This green 

 caterpillar was, however, doubtless that of the privet 

 hawk moth (Sphinx ligustre} ; and as this fine moth is 

 but seldom seen on the wing, it is not perhaps sur- 

 prising that the old fisherman should have supposed 

 that the large day-feeding caterpillar should turn to 

 the comparatively large day-flying dragon-fly. 



The larvae of the dragon-flies have the body compa- 

 ratively short and thick compared to that of the perfect 

 insect ; they are provided with six moderately long 

 scaly legs. They shed their skin, and on becoming pupae 

 they are equally active as before, and have four small 

 scaly pieces, which are the cases in which the large fu- 

 ture wings are concealed. In their aquatic state these 

 insects have a remarkable apparatus attached to the 

 head, enabling them to seize their prey, which consists 

 of other aquatic insects. It is so admirably described 

 by Messrs. Kirby and Spence, that we give their 

 account, with some omissions, rather than attempt its 

 description afresh : " One of the most remarkable 

 prehensile instruments, in which the art and skill of a 

 Divine mechanician are singularly conspicuous, and 

 which appears to be without a parallel in the insect 

 world, may be seen in the under lip of the various 

 species of dragon fly. In other larvae this part is 

 usually small and inconspicuous, and serves merely 

 for retaining the food and assisting in its deglutition, 

 but in these it is by far the largest organ of the 

 mouth, which, when closed, it entirely conceals, and 

 it not only retains, but actually seizes the animal's 

 prey by means of a very singular pair of jaws 

 with which it is furnished. Conceive your under 

 lip (to have recourse, as Reaumur did, on another 

 occasion, to such a comparison) to be horny instead 

 of fleshy, and to be elongated perpendicularly down- 

 wards, so as to wrap over your chin, and extend to 

 its bottom, that this elongation is then expanded into 

 a triangular convex plate attached to it by a joint, so 

 as to bend upwards again, and fold over the face as 

 high as the nose, concealing not only the chin and 



the first-mentioned elongation, but the mouth and 

 part of the cheeks ; conceive, moreover, that to the 

 end of this last-mentioned plate are fixed two other 

 convex ones so broad as to cover the whole nose and 

 temples, that those can open at pleasure transversely, 

 like a pair of jaws, so as to expose the nose and 

 mouth, and that their inner edges, where they meet, 

 are cut into numerous sharp teeth and spines, or 

 armed with one or more long and sharp claws, you 

 will then have as accurate an idea as my powers of 

 description can give of the strange conformation of 

 the under lip in the larvae of the tribes of Libellulina, 

 which conceals the mouth and face precisely as I 

 have supposed a similar construction of your lip would 

 do yours. You will probably admit that your own 

 visage would present an appearance not very engaging 

 while concealed by such a mask ; but it would strike 

 still more awe into the spectators, were they to see 

 you first open the two upper jaw-like plates, which 

 would project from your temples like the blinders of 

 a horse ; and next, having, by means of the joint at 

 your chin, let down the whole apparatus*, and un- 

 covered your face, employ them in seizing any food 

 that presented itself, and conveying it to your mouth. 

 When the insects would make use of it, they unfold 

 it like an arm, catch the prey at which they aim by 

 means of the mandibuliform plates, and then partly 

 refold it, so as to hold the prey to the mouth in a 

 convenient position for the operation of the two pairs 

 of jaws with which they are provided. This conform- 

 ation BO exactly resembles a mask, that, if entomo- 

 logists ever went to masquerades, they could not 

 more effectually relieve the insipidity of such amuse- 

 ments, and attract the attention of the demoiselles, 

 than by appearing at the supper-table with a mask of 

 this construction, and serving themselves by its assist- 

 ance. It would be difficult, to be sure, by mechanism, 

 to supply the place of the muscles with which the 

 insect is amply provided, but Merlin, or his successor, 

 has surmounted greater obstacles. You will admire 

 the wisdom of this admirable contrivance, when you 

 reflect that these larvae are not fitted to pursue their 

 prey with rapidity like most predaceous animals, but 



A, the pupa with Its mask extended. B, the same with the mask 

 closed, and discharging a current of water. 



that they steal upon them, as De Geer observes, as 

 a cat does upon a bird, very slowly, and as if they 

 counted their steps, and then, by a sudden evolution 



Not only is the front piece let down as descnbed by Messrs. 

 Kirby and Spence, but the basal descending piece is subse- 

 quently capable of protrusion by a hinge at its base. 



