rs are always nearly the same on the under surface of their
wings as on the upper; they never try to conceal themselves, but rest on
the upper surfaces of leaves or flowers; and, lastly, they all have
juices which exhale a powerful scent, so that when one kills them by
pinching the body, the liquid that exudes stains the fingers yellow, and
leaves an odour that can only be removed by repeated washings.

Now, there is much direct evidence to show that this odour, though not
very offensive to us, is so to most insect-eating creatures. Mr. Bates
observed that, when set out to dry, specimens of Heliconidae were less
subject to the attacks of vermin; while both he and I noticed that they
were not attacked by insect-eating birds or dragonflies, and that their
wings were not found in the forest paths among the numerous wings of
other butterflies whose bodies had been devoured. Mr. Belt once observed
a pair of birds capturing insects for their young; and although the
Heliconidae swarmed in the vicinity, and from their slow flight could
have been easily caught, not one was ever pursued, although other
butterflies did not escape. His tame monkey also, which would greedily
munch up other butterflies, would never eat the Heliconidae. It would
sometimes smell them, but always rolled them up in its hand and then
dropped them.

We have also some corresponding evidence as to the distastefulness of
the Eastern Danaidae. The Hon. Mr. Justice Newton, who assiduously
collected and took notes upon the Lepidoptera of Bombay, informed Mr.
Butler of the British Museum that the large and swift-flying butterfly
Charaxes psaphon, was continually persecuted by the bulbul, so that he
rarely caught a specimen of this species which had not a piece snipped
out of the hind wings. He offered one to a bulbul which he had in a
cage, and it was greedily devoured, whilst it was only by repeated
persecution that he succeeded in inducing the bird to touch a
Danais.[92]

Besides these three families of butterflies, there are certain groups of
the great genus Papilio--the true swallow-tailed butterflies--which have
all the characteristics of uneatable insects. They have a special
coloration, usually red and black (at least in the females), they fly
slowly, they are very abundant, and they possess a peculiar odour
somewhat like that of the Heliconidae. One of these groups is common in
tropical America, another in tropical Asia, and it is curious that,
althoug