102 



SCHOOL ENTOMOLOGY 



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each other in general color, brown with black markings 

 above and with silver spots on the under side of the 

 hind wings, and all having wings of regular outline. 

 Our largest common ones are Cybele and Idalia, the latter 

 having the hind wings nearly all black. The Angle-wings 

 include several more common species and the name itself 

 briefly describes them. 



The Wood-nymphs are dull brown in color, frail in ap- 

 pearance and faintly marked with round black spots or 



with circles. The Meadow- 

 browns are similar but deeper 

 colored and marked on the angle 

 of the fore wings with yellow 

 circles or spots. 



/Jff The "purple emperors" are 



moderately large and are nor- 

 mally purplish black with white 

 markings. The common one is 

 Astyanax. This is almost entirely 

 purple, but has small white 

 and reddish markings near the 

 angles of the wings. Another 

 one just as common is the Vice- 

 roy, so called because it departs 

 from the color of its nearest 

 relatives and has acquired almost 



exactly the coloration of the monarch. This is explained 

 as a process of natural selection due to the fact that 

 the monarch is distasteful to birds while the group to 

 which the viceroy belongs is not. By acquiring the color 

 of the monarch the viceroy acquires also a certain de- 

 gree of immunity from bird attack. This selective process 

 is termed mimicry. 



FIG. 75. Larva of Viceroy 

 Butterfly Preparing to 

 Form Chrysalis. 



