this species the curved horn on the tail is green, and
closely imitates in its curve the tip of the tendril. But in another
species (Sphinx cranta), which feeds on the fox-grape (Vitis vulpina),
the horn is very long and red, corresponding with the long red-tipped
tendrils of the plant. Both these larvae are green with oblique stripes,
to harmonise with the veined leaves of the vines; but a figure is also
given of the last-named species after it has done feeding, when it is of
a decided brown colour and has entirely lost its horn. This is because
it then descends to the ground to bury itself, and the green colour and
red horn would be conspicuous and dangerous; it therefore loses both at
the last moult. Such a change of colour occurs in many species of
caterpillars. Sometimes the change is seasonal; and, in those which
hibernate with us, the colour of some species, which is brownish in
autumn in adaptation to the fading foliage, becomes green in spring to
harmonise with the newly-opened leaves at that season.[71]

Some of the most curious examples of minute imitation are afforded by
the caterpillars of the geometer moths, which are always brown or
reddish, and resemble in form little twigs of the plant on which they
feed. They have the habit, when at rest, of standing out obliquely from
the branch, to which they hold on by their hind pair of prolegs or
claspers, and remain motionless for hours. Speaking of these protective
resemblances Mr. Jenner Weir says: "After being thirty years an
entomologist I was deceived myself, and took out my pruning scissors to
cut from a plum tree a spur which I thought I had overlooked. This
turned out to be the larva of a geometer two inches long. I showed it
to several members of my family, and defined a space of four inches in
which it was to be seen, but none of them could perceive that it was a
caterpillar."[72]

One more example of a protected caterpillar must be given. Mr. A.
Everett, writing from Sarawak, Borneo, says: "I had a caterpillar
brought me, which, being mixed by my boy with some other things, I took
to be a bit of moss with two exquisite pinky-white seed-capsules; but I
soon saw that it moved, and examining it more closely found out its real
character: it is covered with hair, with two little pink spots on the
upper surface, the general hue being more green. Its motions are very
slow, and when eating the head is withdrawn beneath a fleshy mobile
hood, so that the actio