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

RESEMBLANCES AMONG ANIMALS. 71
cealed. One of the uses of the phosphorescence with
which many insects are furnished, is probably to
frighten away their enemies; for Kirby and Spence
state that a ground beetle (Carabus) has been observed
running round and round a luminous centipede as if
afraid to attack it. An immense number of insects
have stings, and some stingless ants of the genus Polyrachis are armed with strong and sharp spines on the
back, which must render them unpalatable to many of
the smaller insectivorous birds. Many beetles of the
family Curculionidoe have the wing cases and other external parts so excessively hard, that they cannot be
pinned without first drilling a hole to receive the pin,
and it is probable that all such find a protection in
this excessive hardness. Great numbers of insects hide
themselves among the petals of flowers, or in the cracks
of bark and timber; and finally, extensive groups and
even whole orders have a more or less powerful and
disgusting smell and taste, which they either possess
permanently, or can emit at pleasure. The attitudes of
some insects may also protect them, as the habit of
turning up the tail by the harmless rove-beetles (Staphylindidm) no doubt leads other animals besides children to the belief that they can sting. The curious
attitude assumed by sphinx caterpillars is probably a
safeguard, as well as the blood-red tentacles which
can suddenly be thrown out from the neck, by the
caterpillars of all the true swallow-tailed butterflies.
It is among the groups that possess some of these
varied kinds of protection in a high degree, that we