make no suggestion.
It is a very rare species, and I have never seen it. Possibly, in this
case, the blue spots may be an inherited character, and have no
reference to the present habits. They are, at any rate, quite small.

No one who looks at any representations of Hawk-moth caterpillars can
fail to be struck by the peculiar coloring of those belonging to the
Pine Moth, which differ in style of coloring from all other sphinx
larvae, having longitudinal bands of brown and green. Why is this?
Their _habitat_ is different. They feed on the leaves of the pinaster,
and their peculiar coloring offers a general similarity to the brown
twigs and narrow green leaves of a conifer. There are not many species
of butterflies or moths which feed on the pine, but there are a few:
and most, if not all of them, have a very analogous style of coloring
to that of the Pine Moth, while the latter has also tufts of
bluish-green hair which singularly mimic the leaves of the pine. It is
still more remarkable that in a different order of insects we again
find species--for instance one of the saw-flies--which live on the
pine, and in which the same style of coloring is repeated.

Let us now take a single group, and see how far we can explain its
various colors and markings, and what are the lessons which they teach
us. For this purpose, I think I cannot do better than select the larvae
of the Hawk-moths, which have just been the subject of a masterly work
by Dr. Weissmann, from which most of the following facts are taken.

The caterpillars of this group are very different in color--green,
white, yellow, brown, sometimes even gaudy, varied with spots,
patches, streaks, and lines. Now, are these differences merely casual
and accidental, or have they a meaning and a purpose? In many, perhaps
in most cases, the markings serve for the purpose of concealment.
When, indeed, we see caterpillars represented on a white sheet of
paper, or if we put them on a plain table, and focus the eye on them,
the colors and markings would seem, if possible, to render them even
more conspicuous; but amongst the intricate lines and varied colors of
foliage and flowers, and if the insect be a little out of focus, the
effect is very different.

[Illustration: FIG. 3.--THE CATERPILLAR OF THE ELEPHANT HAWK-MOTH
(_Chaerocampa elpenor_). Full grown. Natural size.]

[Illustration: FIG. 4.--THE CATERPILLAR OF THE ELEPHANT HAWK-MOTH
(_Chaerocampa elpenor_). First stage.]