dexterous scalpel
should ever investigate this problem, I can recommend another, even
more singular than that of the Empusa, the Bat and the bird. I refer to
the attitude of certain Wasps and Bees during the night's rest.

An Ammophila with red fore-legs (A. holosericea) is plentiful in my
enclosure towards the end of August and selects a certain
lavender-border for her dormitory. At dusk, especially after a stifling
day, when a storm is brewing, I am sure to find the strange sleeper
settled there. Never was more eccentric attitude adopted for a night's
rest! The mandibles bite right into the lavender-stem. Its square shape
supplies a firmer hold than a round stalk would do. With this one and
only prop, the animal's body juts out stiffly, at full length, with
legs folded. It forms a right angle with the supporting axis, so much
so that the whole weight of the insect, which has turned itself into
the arm of a lever rests upon the mandibles.

The Ammophila sleeps extended in space by virtue of her mighty jaws. It
takes an animal to think of a thing like that, which upsets all our
preconceived ideas of repose. Should the threatening storm burst,
should the stalk sway in the wind, the sleeper is not troubled by her
swinging hammock; at most, she presses her fore-legs for a moment
against the tossed mast. As soon as equilibrium is restored, the
favourite posture, that of the horizontal lever, is resumed, perhaps
the mandibles, like the bird's toes, possess the faculty of gripping
tighter in proportion to the rocking of the wind.

The Ammophila is not the only one to sleep in this singular position,
which is copied by many others--Anthidia (Cotton-bees.--Translator's
Note.), Odyneri (A genus of Mason-wasps.--Translator's Note.), Eucerae
(A species of Burrowing-bees.--Translator's Note.)--and mainly by the
males. All grip a stalk with their mandibles and sleep with their
bodies outstretched and their legs folded back. Some, the stouter
species, allow themselves to rest the tip of their arched abdomen
against the pole.

This visit to the dormitory of certain Wasps and Bees does not explain
the problem of the Empusa; it sets up another one, no less difficult.
It shows us how deficient we are in insight, when it comes to
differentiating between fatigue and rest in the cogs of the animal
machine. The Ammophila, with the static paradox afforded by her
mandibles; the Empusa, with her claws unwearied by ten months' hanging,
leav