man's chief competitors, the insects 



65 



wasps, the caterpillar wasps, nearly all bees, lice, bed-bugs, 

 and many moths and butterflies. Other insects have a wider 

 range; the gypsy moth feeds on a very large variety of plants, 

 while many of the crickets, grasshoppers and cockroaches will 

 consume almost anything of plant or animal origin. It is 

 interesting that no one type of insect is omnivorous; the flies 

 are the most nearly so, but very few of them consume tough 

 or dry substances. 



All of the insects, no matter what their habits, are food for 

 carnivorous t^^es and parasites, and over all of them hangs the 



Figs. 42-44. Three curious deep sea fishes. 

 For explanations of the figures see p. xii. 



constant menace of disease, our common name for the attacks 

 of those lowly organisms, mostly bacteria and fungi, which 

 consume the living flesh. As an illustration of the intensity 

 of the competition I may mention that about forty dift"erent 

 kinds of parasites infest the grubs of the pine saw-fly alone. 

 No accurate idea of insect life is possible without a reali- 



