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ENTOMOLOGY 



Sexual Coloration. The sexes are often distinguished by colora- 

 tional as well as structural differences. Colorational antigeny (this 

 word signifying secondary sexual differences of whatever sort) is most 

 prevalent among butterflies, in which it is the extreme phase of that 



FIG. 237. Pieris protodice; male (on the left) and female (on the right). Natural size. 



differentiation of ornamentation for which Lepidoptera are unrivaled. 



The male of Pieris protodice (Fig. 237) has a few brown spots on the 

 -front wings; the female is checkered with brown on both wings. In 

 Colias philodice (Fig. 238) and C. -eurytheme the marginal black band of 



the front wings is sharp and uninterrupted 

 in the male, but diffuse and interrupted by 

 yellow spots in the female. In the genus 

 Papilio the sexes are often distinguished by 

 colorational differences and in Hesperiidae 

 the males often have an oblique black dash 

 across the middle of each front wing. Callo- 

 samia promethea (Fig. 239), the gipsy moth 

 and many other Lepidoptera exhibit colora- 

 tional antigeny. In not a few Sesiidae the 

 sexes differ greatly in coloration. Thus in 

 the male of the peach tree borer (Aegeria 

 exitiosa) all the wings are colorless and 

 transparent; while in the female the front 

 wings are violet and opaque and the fourth 

 abdominal segment is orange above. The 



same sex may present two types of coloration, as in males of Cyaniris 

 pseudargiolus and females of Papilio glaucus, already mentioned. Papilio 

 merope, of South Africa, is remarkable in having three females, which are 

 entirely different in coloration from one another and from the male. 



FIG. 238. Colias philodice; 

 right fore wing of male (above) 

 and of female (below). Nat- 

 ural size. 



