Chap. XI. 
BUTTERFLIES AND MOTHS. 
411 
Mimickry . — This principle was first made clear in an 
admirable paper by Mr. Bates , 24 who thus threw a flood 
of light on many obscure problems. It had previously 
been observed that certain butterflies in S. America 
belonging to quite distinct families, resembled the Heli- 
conidae so closely in every stripe and shade of colour 
that they could not be distinguished except by an 
experienced entomologist. As the Heliconidae are 
coloured in their usual manner, whilst the others depart 
from the usual colouring of the groups to which they 
belong, it is clear that the latter are the imitators, and 
the Heliconidae the imitated. Mr. Bates further observed 
that the imitating species are comparatively rare, whilst 
the imitated swarm in large numbers ; the two sets 
living mingled together. From the fact of the Heli- 
conidae being conspicuous and beautiful insects, yet 
so numerous in individuals and species, he concluded 
that they must be protected from the attacks of birds 
by some secretion or odour ; and this hypothesis has 
now been confirmed by a considerable body of curious 
evidence . 25 From these considerations Mr. Bates in- 
ferred that the butterflies which imitate the protected 
species had acquired their present marvellously decep- 
tive appearance, through variation and natural selection, 
in order to be mistaken for the protected kinds and 
thus to escape being devoured. No explanation is 
here attempted of the brilliant colours of the imi- 
tated, but only of the imitating butterflies. We must 
account for the colours of the former in the same 
general manner, as in the cases previously discussed in 
this chapter. Since the publication of Mr. Bates’ paper, 
similar and equally striking facts have been observed 
24 ‘ Transact. Linn. Soc.’ yoI. xxiii. 1862, p. 495. 
25 ‘ Proc. Ent. Soc.’ Dec. 3rd, 1866, p. xlv. 
