together.

At maturity, usually near five weeks, the full-fed caterpillar
rests a day, empties the intestines, and races around searching for
a suitable place to locate winter quarters. With burrowing
caterpillars that winter in pupa cases, soft earth or rotting wood
is found and entered by working their way with the heads and
closing it with the hind parts. At the desired depth they push in
all directions with such force that a hollow larger, but shaped as
a hen's egg, is worked out; usually this is six or more inches below
the surface. So compactly is the earth forced back, that fall rains,
winter's alternate freezing and thawing, always a mellowing process,
and spring downpours do not break up the big ball, often larger than
a quart bowl, that surrounds the case of the pupa. It has been
thought by some and recorded, that this ball is held in place by
spinning or an acid ejected by the caterpillar. I never have
heard of any one else who has had my luck in lifting these earth
balls intact, opening, and photographing them and their contents.
I have examined them repeatedly and carefully. I can find not the
slightest trace of spinning or adhesion other than by force.

With one of these balls lifted and divided, we decided what
happened underground by detaining a caterpillar on the surface and
forcing it to transform before us, for this change is not optional.
When the time comes the pupa must evolve. So the caterpillar lies
on the earth, gradually growing shorter, the skin appearing dry
and the horns drooping. There never is a trace of spinning or acid
ejected in the sand buckets. When the change is completed there
begins a violent twisting and squirming. The caterpillar skin opens
in a straight line just behind the head on the back, and by working