esides these Pieridae, Mr. Bates found four true Papilios, seven
Erycinidae, three Castnias (a genus of day-flying moths), and fourteen
species of diurnal Bombycidae, all imitating some species of Heliconidae
which inhabited the same district; and it is to be especially noted that
none of these insects were so abundant as the Heliconidae they
resembled, generally they were far less common, so that Mr. Bates
estimated the proportion in some cases as not one to a thousand. Before
giving an account of the numerous remarkable cases of mimicry in other
parts of the world, and between various groups of insects and of higher
animals, it will be well to explain briefly the use and purport of the
phenomenon, and also the mode by which it has been brought about.

_How Mimicry has been Produced._

The fact has been now established that the Heliconidae possess an
offensive odour and taste, which lead to their being almost entirely
free from attack by insectivorous creatures; they possess a peculiar
form and mode of flight, and do not seek concealment; while their
colours--although very varied, ranging from deep blue-black, with white,
yellow, or vivid red bands and spots, to the most delicate
semitransparent wings adorned with pale brown or yellow markings--are
yet always very distinctive, and unlike those of all the other families
of butterflies in the same country. It is, therefore, clear that if any
other butterflies in the same region, which are eatable and suffer great
persecution from insectivorous animals, should come to resemble any of
these uneatable species so closely as to be mistaken for them by their
enemies, they will obtain thereby immunity from persecution. This is the
obvious and sufficient reason why the imitation is useful, and therefore
why it occurs in nature. We have now to explain how it has probably been
brought about, and also why a still larger number of persecuted groups
have not availed themselves of this simple means of protection.

From the great abundance of the Heliconidae[99] all over tropical
America, the vast number of their genera and species, and their marked
distinctions from all other butterflies, it follows that they constitute
a group of high antiquity, which in the course of ages has become more
and more specialised, and owing to its peculiar advantages has now
become a dominant and aggressive race. But when they first arose from
some ancestral species or group which, owing to the food o