-coloured and
conspicuous insects. The lady-birds (Coccinellidae) and their allies the
Eumorphidae, are often brightly spotted, as if to attract attention; but
they can both emit fluids of a very disagreeable nature, they are
certainly rejected by some birds, and are probably never eaten by any.

The great family of ground beetles (Carabidae) almost all possess a
disagreeable and some a very pungent smell, and a few, called bombardier
beetles, have the peculiar faculty of emitting a jet of very volatile
liquid, which appears like a puff of smoke, and is accompanied by a
distinct crepitating explosion. It is probably because these insects are
mostly nocturnal and predacious that they do not present more vivid
hues. They are chiefly remarkable for brilliant metallic tints or dull
red patches when they are not wholly black, and are therefore very
conspicuous by day, when insect-eaters are kept off by their bad odour
and taste, but are sufficiently invisible at night when it is of
importance that their prey should not become aware of their proximity.

It seems probable that in some cases that which would appear at first to
be a source of danger to its possessor may really be a means of
protection. Many showy and weak-flying butterflies have a very broad
expanse of wing, as in the brilliant blue Morphos of Brazilian forests,
and the large Eastern Papilios; yet these groups are tolerably
plentiful. Now, specimens of these butterflies are often captured with
pierced and broken wings, as if they had been seized by birds from whom
they had escaped; but if the wings had been much smaller in proportion
to the body, it seems probable that the insect would be more frequently
struck or pierced in a vital part, and thus the increased expanse of the
wings may have been indirectly beneficial.

In other cases the capacity of increase in a species is so great that
however many of the perfect insect may be destroyed, there is always
ample means for the continuance of the race. Many of the flesh flies,
gnats, ants, palm-tree weevils and locusts are in this category. The
whole family of Cetoniadae or rose chafers, so full of gaily-coloured
species, are probably saved from attack by a combination of characters.
They fly very rapidly with a zigzag or waving course; they hide
themselves the moment they alight, either in the corolla of flowers, or
in rotten wood, or in cracks and hollows of trees, and they are
generally encased in a very hard