Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

112 rMIMICRY, AND OTHER PROTECTIVE
though it is never perhaps quite equal to that of the
female. In insects the case is very different; they
pair but once in their lives, and the prolonged existence
of the male is in most cases quite unnecessary for the
continuance of the race. The female, however, must
continue to exist long enough to deposit her eggs in a
place adapted for the development and growth of the
progeny. Hence there is a wide difference in the need
for protection in the two sexes; and we should, therefore, expect to find that in some cases the special protection given to the female was in the male less in
amount or altogether wanting. The facts entirely confirm this expectation. In the spectre insects (Phasmide) it is often the females alone that so strikingly
resemble leaves, while the males show only a rude
approximation. The male Diadema misippus is a very
handsome and conspicuous butterfly, without a sign of
protective or imitative colouring, while the female is
entirely unlike her partner, and is one of the most
wonderful cases of mimicry on record, resembling
most accurately the common Danais chrysippus, in
whose company it is often found. So in several species
of South American Pieris, the males are white and
black, of a similar type of colouring to our own
"cabbage". butterflies, while the females are rich
yellow and buff, spotted and marked so as exactly to
resemble species of Heliconidme with which they associate in the forest. In the Malay archipelago is found
a Diadema which had always been considered a male
insect on account of its glossy metallic-blue tints,