276 INDIRECT BENEFITS DERIVED FROM INSECTS. 



(Hydrocorisa Latr.), which glide over the surface of 

 every pool with such rapidity, being gifted with the fa- 

 culty of walking upon the water, Hydrometra, Felia, 

 and Gerris, subsist also upon aquatic insects. A large 

 number of the land-bugs (Geocorisa Latr.) plunge their 

 rostrum into the larvae of Lepidoptera, and suck the 

 contents of their bodies ; and Reduvius personatus, which 

 ought on that account to be encouraged, is particularly 

 fond of the bed-bug. 



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 Libellulina^ 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, 

 which 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 ra- 

 pacious than ever; so that the name given to them in 

 England, " Dragon-flies," seems much more applicable 

 than " Demoiselles," by which the French distinguish 

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

 dress is silky, brilliant and variegated, and trimmed with 

 the finest lace : so far the resemblance holds ; but their 



a Reaum. vi. 400. t. 3638. PLATE XVI. FIG. 5. a. 



