IMPORTANCE AND CHARACTERISTICS OF INSECTS 195 
different this is from the body of the higher animals, as a bird 
or a quadruped or the human being, where no sharp dividing 
line between the thorax or chest and the abdomen can be 
seen from without. Insects have six legs, and this feature 
distinguishes them from their relatives, the spiders, which 
have eight legs, and the centipedes and millipeds, which 
have a great many legs. An insect 
also has a pair of feelers and usually t 
one or two pairs of wings. The feelers “2 : if \ \ Ee 
are attached to the head, and the legs Gaius 
e; 
yt 
and wings to the thorax. br 
_ ABDOMINAL Part oF GRASS- 
Breathing. — Insects have no lungs waecee 
but breathe air by means of a sys- 5y breathing pore; ¢, ear. 
tem of tubes which extend through 
the body and open at the surface for the admission of air. 
In large insects like the grasshopper a row of these open- 
ings may be easily seen along each side of the body. 
