f sand inside; the second, a bolder architect, is
economical of the silk envelope, confines itself to a hanging girdle and
builds course by course. The building-materials are the same: sand and
silk; the surroundings amid which the two artisans work are the same: a
cell in a soil of sandy gravel; yet each of the builders possesses its
individual art, its own plan, its one method.

The nature of the food has no more effect upon the larva's talents than
the environment in which it lives or the materials employed. The proof
of this is furnished by Stiza ruficornis, another builder of cocoons in
grains of sand cemented with silk. This sturdy Wasp digs her burrows in
soft sandstone. Like the Mantis-killing Tachytes, she hunts the various
Mantides of the countryside, consisting mainly of the Praying Mantis;
only her large size requires them to be more fully developed, without
however having attained the form and the dimensions of the adult. She
places three to five of them in each cell.

In solidity and volume her cocoon rivals that of the largest Bembex;
but it differs from it, at first sight, by a singular feature of which
I know no other example. From the side of the shell, which is uniformly
smoothed on every side, a rough knob protrudes, a little clod of sand
stuck on to the rest. The work of Stizus ruficornis can at once be
recognized, among all the other cocoons of a similar nature, by this
protuberance.

Its origin will be explained by the method which the larva follows in
constructing its strong-box. At the beginning, a conical bag is woven
of pure white silk; you might take it for the initial eel-trap of the
Bembeces, only this bag has two openings, a very wide one in front and
another, very narrow one at the side. Through the front opening the
Stizus provides itself with sand as and when it spends this material on
encrusting the interior. This strengthens the cocoon; and the cap
which closes it is made next. So far it is exactly like the work of the
Bembex. We now have the worker enclosed, engaged in perfecting the inner
wall. For these final touches a little more sand is needed. It obtains
it from outside by means of the aperture which it has taken the
precaution of contriving in the side of its building, a narrow
dormer-window just large enough to allow its slender neck to pass. When
the store has been taken in, this accessory orifice, which is used only
during the last few moments, is closed with a mouthful of