The Descent of Man

33) that, "the captured flies utter a peculiar
plaintive note, and that this sound causes other
flies to disappear.")
ORDER, HEMIPTERA (FIELD-BUGS).
Mr. J.W. Douglas, who has particularly attended
to the British species, has kindly given me
an account of their sexual differences. The males
of some species are furnished with wings,
whilst the females are wingless; the sexes differ
in the form of their bodies, elytra, antennae and
tarsi; but as the signification of these differences
are unknown, they may be here passed
over. The females are generally larger and more
robust than the males. With British, and, as far
as Mr. Douglas knows, with exotic species, the
sexes do not commonly differ much in colour;
but in about six British species the male is considerably
darker than the female, and in about
four other species the female is darker than the
male. Both sexes of some species are beautifully