ceiling, the upper part of the cocoon cannot be fashioned, because the
worker lacks the necessary points of support. Under these conditions my
Scolia-grubs contrive at most to upholster their little pit with a thick
down of reddish silk. Discouraged by futile endeavours, some of them die.
It is as if they had been killed by the silk which they omit to disgorge
because they are unable to make the right use of it. This, if we were not
watchful, would be a very frequent cause of failure in our attempts at
artificial rearing. But, once the danger has been perceived, the remedy is
simple. I make a ceiling over the cavity by laying a short strip of paper
above it. If I want to see how matters are progressing, I bend the strip
into a semicircle, into a half-cylinder with open ends. Those who wish to
play the breeder for themselves will be able to profit by these little
practical details.

In twenty-four hours the cocoon is finished; at least, it no longer allows
us to see the grub, which is doubtless making the walls of its dwelling
still thicker. At first the cocoon is a vivid red; later it changes to a
light chestnut-brown. Its form is that of an ellipsoid, with a major axis
26 millimetres in length, while the minor axis measures 11 millimetres.
(1.014 x .429 inch.--Translator's Note.) These dimensions, which
incidentally are inclined to vary slightly, are those of the female
cocoons. In the other sex they are smaller and may measure as little as 17
millimetres in length by 7 millimetres in width. (.663 x .273 inch.--
Translator's Note.)

The two ends of the ellipsoid have the same form, so much so that it is
only thanks to an individual peculiarity, independent of the shape, that we
can tell the cephalic from the anal extremity. The cephalic pole is
flexible and yields to the pressure of my tweezers; the anal pole is hard
and unyielding. The wrapper is double, as in the cocoons of the Sphex. (Cf.