INDIRECT BENEFITS DERIVED FROM INSECTS. 275 



But of all the insects that are locomotive and pursue 

 their prey in every state, none are greater enemies of 

 their fellow tribes than the LibelluUdce^ and none are 

 provided with more powerful and singular instruments 

 of assault. In the larva and pupa states, during which 

 they live in the water and prey upon aquatic insects, 

 they are furnished with two pair of strong jaws, covered 

 by a kind of mask armed with a pair of forceps or claws, 

 w hich the animal has the power of pushing from it to 

 catch any thing at a distance ^. When an aquatic insect 

 passes within its reach, it suddenly darts forth the mask, 

 opens the forceps, seizes the unfortunate victim, and 

 brings it within the action of its jaws. 



When they assume the imago state, their habits do 

 not, like those of the white ants, become more mild and 

 gentle, but on the contrary are more sanguinary and 

 rapacious than ever ; so that the name given to them 

 in England, " Dragon-flies," seems much more appli- 

 cable than " Demoiselles," by which the French distin- 

 guish them . Their motions it is true are light and airy ; 

 their dress is silky, brilliant and variegated, and trim- 

 med with the finest lace : — so far the resemblance holds ; 

 but their purpose, except at the time of love, is always 

 destruction, in which surely they have no resemblance 

 to the ladies. I have been much amused by observing 

 the proceedings of a species not uncommon here, which 

 however is nondescript. It keeps wheeling round and 

 round, and backwards and forwards, over a consider- 

 able portion of the pool it frequents. If one of the same 

 species comes in its way, a battle ensues ; if other spe- 

 cies of Libellulidce presunfte to approach, it drives them 



' Reaum. vi. 400. t. 36—38. Plate XVI. Fig. 5. r. 

 T 2 



