some species make a peculiar singing noise whilst pursuing the females.
ORDER, COLEOPTERA (BEETLES).
Many beetles are coloured so as to resemble the surfaces which they
habitually frequent, and they thus escape detection by their enemies.
Other species, for instance diamond-beetles, are ornamented with
splendid colours, which are often arranged in stripes, spots, crosses,
and other elegant patterns. Such colours can hardly serve directly as a
protection, except in the case of certain flower-feeding species; but
they may serve as a warning or means of recognition, on the same
principle as the phosphorescence of the glow-worm. As with beetles the
colours of the two sexes are generally alike, we have no evidence that
they have been gained through sexual selection; but this is at least
possible, for they have been developed in one sex and then transferred
to the other; and this view is even in some degree probable in those
groups which possess other well-marked secondary sexual characters.
Blind beetles, which cannot of course behold each other s beauty,
never, as I hear from Mr. Waterhouse, jun., exhibit bright colours,
though they often have polished coats; but the explanation of their
obscurity may be that they generally inhabit caves and other obscure
stations.
Some Longicorns, especially certain Prionidae, offer an exception to
the rule that the sexes of beetles do not differ in colour. Most of
these insects are large and splendidly coloured. The males in the genus
Pyrodes (63. Pyrodes pulcherrimus, in which the sexes differ
conspicuously, has been described by Mr. Bates in Transact. Ent. Soc.
1869, p. 50. I will specify the few other cases in which I have heard
of a difference in colour between the sexes of beetles. Kirby and
Spence ( Introduct. to Entomology, vol. iii. p. 301) mention a
Cantharis, Meloe, Rhagium, and the Leptura testacea; the male of the
latter being testaceous, with a black thorax, and the female of a dull
red all over. These two latter beetles belong to the family of
Longicorns. Messrs. R. Trimen and Waterhouse, jun., inform me of two
Lamellicorns, viz., a Peritrichia and Trichius, the male of the latter
being more obscurely coloured than the female. In Tillus elongatus the
male is black, and the female always, as it is believed, of a dark blue
colour, with a red thorax. The male, also, of Orsodacna atra, as I hear
from Mr. Walsh, is black, the female (the so-called O. ruficollis)
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