272 INDIRECT BENEFITS DERIVED FROM INSECTS. 



them under every form. These begin the work of de- 

 struction when they are larvae, and continue it during 

 the whole of their existence. — The earwig that haunts 

 every close place in our gardens, and defiles whatever 

 it enters, probably in some degree makes up for its ra- 

 vages bv diminishing the number of other insects. The 

 cowardly and cruel Mantis, which runs away from an 

 ant, will destroy in abundance helpless flies, using its 

 anterior tibiae, which with the thigh form a kind of for- 

 ceps, to seize its prey. The water-scorpions (Nepa, 

 Ranatra, and Naucoris), whose fore legs are made like 

 those of the Mantis, the water-boatman (Noto?iecta\ 

 which always swims upon its back, and the Sigara, all 

 live by rapine, and prey upon aquatic insects. Some of 

 this tribe are so savage that they seem to love destruction 

 for its own sake. One (Nepa cinerea) which was put 

 into a basin of water with several young tadpoles, killed 

 them all without attempting to eat one. 



Those remarkable genera of the extensive tribe of 

 bugs (Cimicidcv), which glide over the surface of every 

 pool with such rapidity, being gifted with the faculty of 

 walking upon the water, the Hydrometra, Velio,, and 

 Gerris of Latreille, subsist also upon aquatic insects. A 

 large number of the same tribe plunge their rostrum into 

 the larvae of Lepidojjfera, and suck the contents of their 

 bodies ; and Reduvius personates, 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 Libelhdidce, and none are 

 provided with more powerful and singular instruments 



