WHAT AN INSECT IS 247 



stage of their existence. When wings are present, there 

 may be either one or two pairs. Nearly all insects have 

 legs ; six is the usual number. These two characteristics, 

 the presence of wings and of six legs, are sufficient to identify 

 an insect. There are insects, however, that lack wings 

 and legs. 



Spiders and mites not insects. The only creatures likely 

 to be mistaken for insects are the spiders and mites. These 

 never have wings and always have eight legs. By simply 

 counting legs, then, spiders may be separated from the 

 wingless insects. 



The principal parts of an insect. The body is divided 

 into three parts: the head, the thorax, and the abdrf men 

 (Fig. 164). The head bears the eyes, the 

 anten'n<E, or feelers, and the montli 

 parts. To the tho'rax, or chest, of the 

 insect are attached the wings and the 

 legs, but both wings and legs are en- 

 tirely wanting in some insects. 



The eyes and antennae. The eye is 

 made up of a large number of simple 

 eyes, so closely crowded together that 



r i . it i FIG. 164. THE PARTS 



they form what is called a compound OF AN I NSE CT 



eye. As a whole it is shaped somewhat 



like half a raspberry, dewberry, or blackberry. The shape 



of each part of the eye is something like that of a cell in 



honeycomb. 



The antennae bear the sense organs, which correspond to 

 our touch, smell, and probably hearing also. One reason 

 why the name " feelers " is often applied to these organs is 



