200 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



skilled obsei-vers who have studied them in their native haunts has 

 ever seen a bird attack them, and the only ground for believing that 

 they are attacked rests upon the rather dubious evidence of a few 

 specimens found by Fritz Miiller having symmetrical pieces 

 apparently bitten out of the hind wings. Belt ('74) observed that a 

 pair of birds which were bringing large numbers of dragon-flies and 

 butterflies to their young never brought any of the Heliconidae, 

 although these Avere abundant in the neighborhood. In fact, Belt 

 was able to discover only one enemy of these butterflies, and that 

 was a yellow and black wasp, which caught them and stored them 

 up in its nest to feed its young. The Heliconidae then, in spite of 

 their weak structure, conspicuous colors, and slow flight, enjoy a 

 peculiar immunity. 



As is well known. Bates ('62) first called attention to the fact that 

 the Heliconidae were " mimicked " or imitated both in color-pattern 

 and shape of wings by a number of other genera of butterflies and 

 even moths. Bates had no difticulty in showing that this mimicry 

 might easily be explained upon the ground that the Heliconidae, on 

 account of their bad taste and smell, were immune from the attacks 

 of birds and other insectivorous animals, and that therefore it gave a 

 peculiar advantage to a butterfly belonging to any other group not 

 thus protected, to assume the shape and coloration of the Heliconidae ; 

 for then the bu-ds could not perceive any difference between it and 

 the true Heliconidae. Bates found that fifteen species of Pieridae 

 belonging to the genera Leptalis and Euterpe, four Papilios, seven 

 Erycinidae, and among diurnal inoths three Castnias and fourteen 

 Bombycidae imitate each some distinct species of the Heliconidae 

 occupving the same district. He also found that all of these insects 

 were much rarer than the Heliconidae which they imitated. In some 

 cases, indeed, he estimated the proportion to be less than one to a 

 thousand. Wallace ('89, p. 265), who has added so much to our 

 knowledge of this subject, aptly defines this kind of mimicry as an 

 " exceptional form of protective resemblance." 



But by far the most remarkable discovery made by Bates was the 

 fact, that species belonging to different genera of the Heliconidae 

 themselves mimic one another. Xeither Bates nor Wallace was 

 able to give any satisfactory explanation of the cause of this latter 

 form oi mimicry, for all of the genera of the Heliconidae are 

 immune. They therefore supposed it to be due to ^' unknown local 

 causes," or similarity of environment and conditions of life. 



