16 NORTH AMERICAN INSECTS. 



different species. If we adopt the general rule, that on an 

 average three species of Insects dwell on each species of 

 plants (and on some plants we find three or four times as 

 many), we can easily see that such an enormous number 

 can not prove too small an estimate, when we consider that 

 there are now known between forty and fifty thousand spe- 

 cies of plants. 



The nourishment of Insects is as varied and different as 

 that of larger animals. A great number of them are car- 

 nivorous, and prey upon other insects ; or they feed on dirt, 

 dead bodies, or decayed wood, as the dung-beetles, flies, ants, 

 and the larvse of the stag-beetle ; or they feed on plants, as 

 the Way-beetle, plant-lice, etc. 



In regard to the venom of Insects, we find a number of 

 them provided with organs for biting or stinging, which oc- 

 casion inflammatory tumors and poisoned wounds, which 

 are ofttimes dangerous, and sometimes fatal to man, as, for 

 instance, the sting of bees, wasps, and mosquitoes. 



The faculty called Instinct, which belongs to all animals, 

 and by which, from an internal impulse, and without in- 

 struction, they perform certain actions tending to their own 

 support or that of their offspring, is also found in Insects, 

 as well as some faculties of the mind which would astonish 

 an observer. Thus, when the Tumble-beetle in vain tries 

 to roll its little ball up a hill, it runs for assistance, and 

 brings back with it two or three other ones who roll up the 

 ball in concert with it, but as soon as they have succeeded, 

 the assistants fly away, and the first one continues his work 

 alone. Bees, Wasps, and Ants defend themselves with great 

 courage, and woe to him who attacks a wasp's nest ! Some 

 flower-beetles, like opossums, pretend to be dead when you 

 catch them, or at your approach conceal themselves behind 

 a leaf, or fall to the ground as if dead. Some have even 

 memory, and know perfectly well the one who takes care 

 of them, as, for instance, the Bees. The nests and dwell- 



