INSECTA 



115 



Those portions of the cuticle which do not contain much 

 chitin are easily bent, thus permitting motion between the 

 segments of the body and of the appendages. 



All insects have hairs scattered more or less abundantly or 

 regularly over the body. In Lepidoptera the hairs are modified 

 into scales, as is shown on the wings of a butterfly, where " all 

 the gradations from hair to scale can be found by going from 

 the base out to the distal area of the wing."^ 



Self-defense (Fig. 86) is by various methods and organs, 

 which will suggest themselves to the student from his past 

 experience. When insects cannot sting or bite, they often 



Fig. 87. — Al'aus ocula'tus and larva, showing eye-spots. (After Harris.) 



defend themselves by threatening attitudes. In some cases 

 one is reminded, at first sight, of a snake's head, and retreats 

 in terror. The " eye-spots " (Fig. 87) and " horns " (Fig. 88) 

 on many insects are probably for the purpose of terrifying ap- 

 pearance. 



Protective Coloration. — Insects attract attention by the 

 variety and intensity of their colors and by their numerous, 

 interesting, and often l)eautiful color-patterns. Many natural- 

 ists believe, and have confirmed their opinions by observation 

 and experiment, that the variety of color and color-patterns of 



1 Kellogg, p. 592. 



