274 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
skilled observers 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 Muller 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 were 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 difficulty 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 birds 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 moths three Castnias and fourteen 
Bombycidae imitate each some distinct species of the Heliconidae 
occupying the same district. He also found that all of these insects 
were much rarer than the Heliconidae Avhicli 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. Neither Bates nor Wallace was 
able to give any satisfactory explanation of the cause of this latter 
form of 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. 
