The Tachytes builds in quite another fashion, although its work, once
finished, does not differ from that of the Bembex. The larva surrounds
itself, to begin with, about the middle of its body with a silken girdle
which a number of threads, very irregularly distributed, hold in place and
connect with the walls of the cell. Sand is collected, within reach of the
worker, on this general scaffolding. Then begins the work of minor masonry,
with grains of sand for rubble and the secretion of the spinnerets for
cement. The first course is laid upon the fore-edge of the suspensory ring.
When the circle is completed, a second course of grains of sand, stuck
together by the fluid silk, is raised upon the hardened edge of what has
just been done. Thus the work proceeds, by ring-shaped courses, laid edge
to edge, until the cocoon, having acquired half of its proper length, is
rounded into a cap and finally is closed. The building-methods of the
Tachytes-larva remind me of a mason constructing a round chimney, a narrow
tower of which he occupies the centre. Turning on his own axis and using
the materials placed to his hand, he encloses himself little by little in
his sheath of masonry. In the same way the worker encloses itself in its
mosaic. To build the second half of the cocoon, the larva turns round and
builds in the same way on the other edge of the original ring. In about
thirty-six hours the solid shell is completed.

I am rather interested to see the Bembex and the Tachytes, two workers in
the same guild, employ such different methods to achieve the same result.
The first begins by weaving an eel-trap of pure silk and next encrusts the
grains of 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