4 BUTTERFLIES IN DISGUISE 



for spot. Now his field observations showed him 

 that the mimicking species belonged to a group 

 of butterflies very subject to attack by birds and 

 other foes, while the group which they mimicked 

 had an offensive odor and apparently a taste 

 obnoxious to insectivorous animals, so as to be 

 exempt practically from their attacks. This was 

 shown partly by their exceptional abundance, 

 which did not seem to accord with slow and easy 

 flight and conspicuous coloring, features that nat- 

 urally would render them an easy prey to their 

 enemies. That these butterflies were truly dis- 

 tasteful to birds has been shown again and again. 

 Thus Belt says, in his "Naturalist in Nicara- 

 gua " : — 



" I had an opportunity of proving in Brazil that some 

 birds, if not all, reject the Heliconii butterflies, which 

 are closely resembled by butterflies of other famiUes 

 and by moths. I observed a pair of birds that were 

 bringing butterflies and dragonflies to their young, and 

 although the Heliconii swarmed in the neighborhood, 

 and are of weak flight, so as to be easily caught, the 

 birds never brought one to their nest. I had a still bet- 

 ter means of testing both these and other insects that are 

 mimicked in Nicaragua. The tame, white-faced monkey 

 I have already mentioned was extremely fond of insects, 



