INSECTA 



117 



chemical composition; or physical, depending upon the structural 

 or physical make-up; or it may be due to a combination of 

 both of these. In the most highly colored group of insects, 

 the Lepidoptera, the color is due to the chemical substances 

 (pigment granules), to the structural character of the scale 



Fig. 90. — The protective resemblance of the leaf -butterfly (Kal'lima). 

 (Holder, after Wallace.) 



walls (striae), and to the overlapping (lamination) of the scales 

 laterally, as well as to the overlapping of the tips of the scales 

 in one row over the bases of the scales of another row. 



" The blacks, browns, yellows, and dull reds of butterflies and 

 moths are produced chiefly by the pigments (chemical colors), 

 while the brilliant metallic colors, the iridescent blues and 



