ridges which eat many kinds of caterpillars seem to
have an absolute dread of that of the common currant moth, which they
will never touch, and tomtits as well as other small birds appear never
to eat the same species. In the case of the Heliconidae, however, we
have some direct evidence to the same effect. In the Brazilian forests
there are great numbers of insectivorous birds--as jacamars, trogons,
and puffbirds--which catch insects on the wing, and that they destroy
many butterflies is indicated by the fact that the wings of these
insects are often found on the ground where their bodies have been
devoured. But among these there are no wings of Heliconidae, while those
of the large showy Nymphalidae, which have a much swifter flight, are
often met with. Again, a gentleman who had recently returned from Brazil
stated at a meeting of the Entomological Society that he once observed a
pair of puffbirds catching butterflies, which they brought to their nest
to feed their young; yet during half an hour they never brought one of
the Heliconidae, which were flying lazily about in great numbers, and
which they could have captured more easily than any others. It was this
circumstance that led Mr. Belt to observe them so long, as he could not
understand why the most common insects should be altogether passed by.
Mr. Bates also tells us that he never saw them molested by lizards or
predacious flies, which often pounce on other butterflies.

If, therefore, we accept it as highly probable (if not proved) that the
Heliconidae are very greatly protected from attack by their peculiar
odour and taste, we find it much more easy to understand their chief
characteristics--their great abundance, their slow flight, their gaudy
colours, and the entire absence of protective tints on their under
surfaces. This property places them somewhat in the position of those
curious wingless birds of oceanic islands, the dodo, the apteryx, and
the moas, which are with great reason supposed to have lost the power of
flight on account of the absence of carnivorous quadrupeds. Our
butterflies have been protected in a different way, but quite as
effectually; and the result has been that as there has been nothing to
escape from, there has been no weeding out of slow flyers, and as there
has been nothing to hide from, there has been no extermination of the
bright-coloured varieties, and no preservation of such as tended to
assimilate with surrounding objects.