ARTHROPODA 



219 



Generally there is more or less sexual dimorphism ; the males 

 and females differ in the form and size of the antennae and also 

 in the general size, form, and color of the body. The male is 

 provided with a large, horn}- penis. The larvae are more or less 

 grublike, with or without legs, and usually have mouth parts 

 which are formed for biting or 

 gnawing. Many larvae live several 

 years before passing into pupae. 

 The adult beetles vary from minute 

 species only one or two millimeters 

 in length to the huge stag beetles of 

 the tropics, measuring fifteen centi- 

 meters. Many beetles are very 

 beautiful, being a brilliant metallic 

 green or red in color ; the goldsmith 

 beetle is a bright yellow above and 

 green below. Some South Ameri- 

 can beetles owe their color to minute 

 scales, as in the diamond beetle, 

 whose black elytra are covered with 

 minute pits, and these are lined with 

 very small scales of a predominant green color, but refracting 

 the light so as to give various brilliant prismatic effects ; this 

 beetle is' about three centimeters in length. 



Fig. 223. Ateuchus {Scarabaus) sacer, 

 the sacred scarab beetle. (From 

 Ludwig-Leunis' Synopsis der Thier- 

 kunde.) 



FlG. 224. Anthrenm scrop/iularice, the carpet beetle, a, b, larva-: c, pupa; J, imago. 

 (After Riley, trom Parker and Haswell's Manual.) 



While the majority of the beetles are distinctly terrestrial in- 

 sects, some live in the water and breathe there by means of a 



