

COLOR AND COLORATION 



There is no longer any doubt, it may be added, as to the specific 

 identity of these forms. 



Next to Lepidoptera, Odonata most frequently show colorational 

 antigeny. The male of Calopteryx maculata is velvety black; the female 

 smoky, with a white pterostigmatal spot. Among Coleoptera, the male 

 of Hoplia trifasciata is grayish and the female reddish brown; a few 

 more examples might be 

 given, though sexual dif- 

 ferences in coloration are 

 comparatively rare among 

 beetles. OfHymenoptera, 

 some of the Tenthredinidae 

 exhibit colorational 

 antigeny. 



Among tropical butter- 

 flies there are not a few 

 instances in which the 

 special coloration of the 

 female is adaptive har- 

 monizing with the sur- 

 roundings or else imitating 

 with remarkable precision 

 the coloration of another 

 species which is known 

 to be immune from the 

 attacks of birds as de- 

 scribed beyond. In this 

 way, as Wallace suggests, 

 the egg-laden females may 

 escape destruction, as they 

 sluggishly seek the proper 

 plants upon which to lay 

 their eggs. Here would 

 be a fair field for the operation of natural selection. 



In most insects, however, sexual differences in coloration are ap- 

 parently of no protective value and are usually so trivial and variable 

 as probably to be of no use for recognition purposes. The usual state- 

 ment that these differences facilitate sexual recognition is a pure as- 

 sumption, in the case of insects, and one that is inadequate in spite of 

 its plausibility, for (i) it is extremely improbable from our present 



FIG. 239. Callosamia promethea. A, male, clinging to 

 cocoon; B, female. Reduced. 



