The Descent of Man

fully explained. The white female of the Cycnia
resembles the very common Spilosoma menthrasti,
both sexes of which are white; and Mr.
Stainton observed that this latter moth was rejected
with utter disgust by a whole brood of
young turkeys, which were fond of eating other
moths; so that if the Cycnia was commonly
mistaken by British birds for the Spilosoma, it
would escape being devoured, and its white
deceptive colour would thus be highly beneficial.),
and these belong to groups which generally
fly about during the afternoon. On the other
hand, in many genera, as Mr. Stainton informs
me, the males have the hind-wings whiter than
those of the female—of which fact Agrotis exclamationis
offers a good instance. In the Ghost
Moth (Hepialus humuli) the difference is more
strongly marked; the males being white, and
the females yellow with darker markings. (21. It
is remarkable, that in the Shetland Islands the
male of this moth, instead of differing widely
from the female, frequently resembles her clo-