130 Life and Tmmortahty. 
So securely does the caterpillar hold on to its house, that 
one would suppose that its body was lashed to the inside. But 
no, its body is unhampered, for it can turn itself easily around 
in its case, and go out at either end, although the head is 
generally directed upward. It clings to the inside with the 
hooks upon its hinder feet, and so tenaciously, too, that the 
writer has never been able to pull one out, being checked by 
the fear of tearing the creature in two. And now to the 
mode of attaching the leaf-cuttings to the case. This is 
always done at or near the mouth of the sac. The Ephemera- 
form larva is a growing creature, unlike the moth itself, which 
emerges a perfect insect of full growth. It commences life as 
a small worm, eats small quantities, and, as may be observed, 
down towards the foot of the case sews on very small tags. 
But after it has fastened on these pieces to the mouth, it 
grows itself, and so also does the case, which it continually 
stretches and enlarges. Hence the mouth of the case is 
continually changing, moving upward as the worm feeds, so 
that the pieces sewed upon the cap of the case thus appear, 
in an adult caterpillar, precisely as they are seen scattered 
along the outside from top to bottom. And now, as to how 
the pieces are put into the case, I shall endeavor to explain. 
That the worm cuts purposely through the twig which it 
needs for the case, I feel certain. Of course the outer or 
detached part drops down. But, while eating, the worm 
frequently, quite constantly, indeed, spreads its viscid silk 
along the leaf and so keeps it attached on both sides to the 
upper rim of the sac, or to its own mouth-parts, and thus the 
tip of the twig or leaf, instead of falling to the ground when 
it is severed from the stem, simply drops alongside of the 
case, to which it is held by the slight filament that attaches 
it to the sac, or, as happens in many instances, remains 
attached to the caterpillar’s spinneret. In either case the 
leaf, twig or stem remains, and, after being drawn up, adjusted 
and tightened by the worm, adheres tightly. As the creat- 
ure is forever moving its spinning-tubes around the top of 
