tells them where they are. So long as their
lips do not chance to light upon the pasture-land, not one of them
settles there, though he be ravenous. They do not hasten to food which
they have scented from afar; they stop at a branch which they encounter
on their way.

Apart from sight and smell, what remains to guide them in returning to
the nest? The ribbon spun on the road. In the Cretan labyrinth, Theseus
would have been lost but for the clue of thread with which Ariadne
supplied him. The spreading maze of the pine-needles is, especially at
night, as inextricable a labyrinth as that constructed for Minos. The
Processionary finds his way through it, without the possibility of a
mistake, by the aid of his bit of silk. At the time for going home,
each easily recovers either his own thread or one or other of the
neighbouring threads, spread fanwise by the diverging herd; one by one
the scattered tribe line up on the common ribbon, which started from
the nest; and the sated caravan finds its way back to the manor with
absolute certainty.

Longer expeditions are made in the daytime, even in winter, if the
weather be fine. Our caterpillars then come down from the tree, venture
on the ground, march in procession for a distance of thirty yards or
so. The object of these sallies is not to look for food, for the native
pine-tree is far from being exhausted: the shorn branches hardly count
amid the vast leafage. Moreover, the caterpillars observe complete
abstinence till nightfall. The trippers have no other object than a
constitutional, a pilgrimage to the outskirts to see what these are
like, possibly an inspection of the locality where, later on, they mean
to bury themselves in the sand for their metamorphosis.

It goes without saying that, in these greater evolutions, the guiding
cord is not neglected. It is now more necessary than ever. All
contribute to it from the produce of their spinnerets, as is the
invariable rule whenever there is a progression. Not one takes a step
forward without fixing to the path the thread from his lips.

If the series forming the procession be at all long, the ribbon is
dilated sufficiently to make it easy to find; nevertheless, on the
homeward journey, it is not picked up without some hesitation. For
observe that the caterpillars when on the march never turn completely;
to wheel round on their tight-rope is a method utterly unknown to them.
In order therefore to regain the road already cov