276 INDIRECT BENEFITS DERIVED FROM INSECTS. 



away, and it is continually engaged in catching Pliry- 

 ganeae and other insects (for the species of this tribe 

 all catch their prey when on the w ing, and their large 

 eyes seem given them to enable them the more readily 

 to do this,) that fly over the water, pulling off their 

 wings with great adroitness and devouring in an instant 

 the contents of the body. From the number of insects 

 of this tribe which are every where to be observed, we 

 may conjecture how useful they must be in preventing 

 too great a multiplication of the other species of the 

 class to which they belong. 



Lastly, under this head, not to dwell upon some other 

 apterous genera, devourers of insects, as the scorpion 

 and centipede, Phalangium and Solpuga, must be enu- 

 merated the whole Avorld of Spiders, extremely nu- 

 merous both in species and individuals, which subsist 

 entirely upon insects, spreading with infinite art and 

 skill their nets and webs to arrest the flight of the lieed- 

 less and unwary summer tribes that fill the air, which 

 are hourly caught by thousands in their toils ; one of 

 them (Aranea 13-guttata Rossi) we are told, even at- 

 tacking the redoubted Scorpion ^, 



So much for the insect benefactors to whom it is given 

 in charge to keep the animals of their own class within 

 their proper limits; and I cannot doubt that you will 

 recognise the goodness of the Great Parent in provid- 

 ing such an army of counterchecks to the natural ten- 

 dency of almost all insects to incalculable increase. But 

 before I quit this subject I must call your attention to 

 what may be denominated cannibal inserJs^ since in spit(! 

 of thooe declaimers who would persuade us that man is 



' Thiebaut de Eemeaitd'? Vavage to Elba, p. 31. 



