As soon as my Imperialis larvae had hatched, I gave them various kinds of
foliage, plane-tree, oak, pine, sallow, etc. At first they did not touch
any kind of foliage, or they did not seem to touch any; and I was afraid
I should be unable to rear them; but on the second or third day of their
existence, they made up their minds and decided upon eating the foliage
of some of the European trees I had offered them. They attacked oak,
sallow, and pine, but did not touch the plane-tree leaves. In America,
the larvae of Imperialis feed on button-wood, which is the American
plane-tree (_Platanus occidentalis_), yet they did not take to _Platanus
orientalis_. After a little time I reduced the foliage to oak and sallow
branches, and ultimately gave them the sallow (_Salix caprea_) only, on
which they thrived very well. I was pleased with this success; as I had
previously read in a volume of the "Naturalist's Library" a description
of _Ceratocampa imperialis_, which ends as follows: "The caterpillars
are not common, and are the most difficult to bring to perfection in
confinement, as they will not eat in that situation; and, even if they
change into a chrysalis, they die afterward."

Before I finish with _C. imperialis_, I must mention a peculiar fact.
During the first stage, and, I think, also during the second, several
larvae disappeared without leaving any traces. I also saw two smaller
larvae held tight by the hind claspers of two larger ones. The larvae thus
held and pressed were perfectly dead when I observed them, and I removed
them. My impression then was that these larvae were carnivorous, not
from this last fact alone, as I had previously observed it with larvae
of Catocalae when they are too crowded, but from the fact that some had
disappeared entirely from the glass under which they were confined. I
began to reduce their numbers, and put six only under each glass, so as
to be able to watch them better. Whether I had made a mistake or not
previously to this I do not exactly know; but from this moment the