SHEATH-WINGED INSECTS
“I show you here the scarab, clothed all in black. Passionate lover of
the sun, it rarely strays beyond the regions bordering on the
Mediterranean. It belongs to the band of scavengers, a group of
handsome insects which, feeding on ordure, are charged with the
sanitation of the greensward defiled by grazing herds.
“Its favorite dish is the dung of horses and mules. With the toothed
edges of its head it rummages in the dung; with its wide, serrate fore
legs it cuts up this material, kneads it, and molds it into a ball
about as large as an apricot. This done, the next thing is to seek out
some quiet retreat far from the hubbub of its fellows who have been
drawn to the spot for as much as a kilometer round about by the odor;
and of course the booty must be trundled away to this secure retreat,
there to be eaten at ease, without fear of predatory assaults from the
envious.
“This task is performed in couples. One hooks on to the globule in
front and pulls with head up; the other pushes from behind with head
down. Heave ho! It starts, it rolls, under the combined efforts of the
two partners. On the down grade the load again and again runs away with
the team, which falls headlong, gets up again, and catches hold of the
cargo once more with an ardor that nothing can discourage. Under the
rays of a scorching sun this store of provision is thus dragged a long
distance over the sand, across the greensward, and over ruts. Perhaps
the scarabs find their bread at first not sufficiently compact, and
seek to give it consistency by rolling it on the ground. Every one
according to his fancy.
“At last a favorable spot is selected in a sandy tract. One of the two
proprietors hollows out in all haste a dining-room, while the other
stands guard without over the globular treasure, ready to defend it
stoutly against any chance marauder. As soon as the dining-room is
ready the provisions are stored away there, after which the two
colleagues shut themselves up in their domicile, safe from unwelcome
visitors, closing their door with sand. So there they are at table,
with their heap of victuals in front of them; and now for a good feast!
When the board is bare again, the two banqueters leave their dugout to
gather together a new globule and resume their feasting.
“The scarab is not found everywhere, the more’s the pity, for its
manner of life is very curious to watch. Wanting this manufacturer of
globules, we nevertheless do have everywhere other scavengers which
work in somewhat similar fashion. Out of ordure they put together
little balls of the size of a cherry, and sometimes they roll away
their plunder, as does the scarab, bury it in the ground, and there
regale themselves on it. Their trade of making these little balls or
pills has given them the expressive name of pill-mixers.
“Let us pass on to other kinds. This one, for example, is called the
calosoma. By reason of the elegance of its form and the richness of its
coloring it is one of the most beautiful insects of our region. Its
back has the brilliance of a gem such as no jeweler ever possessed. One
would really take it to be made of gold, but gold of a peculiar sort
and much richer than ours, flashing as it does with red, green, and
purple glints. There is nothing to compare with this dazzling costume.
It should be added that if the insect is taken between the fingers it
emits, as a means of defense, a strong odor reminding one of a
chemist’s disagreeable drugs.
“The calosoma does not share the scarab’s peaceful habits: it is an
ardent hunter and leads a life of carnage. Its prey is the caterpillar,
the bigger the better, whether smooth-skinned or hairy. If you happen
to find a calosoma, put it into a good-sized bottle and give it for
dinner a lusty young caterpillar as large as your finger. You will see
with what ferocious satisfaction this drinker of blood will disembowel
the poor worm, despite all its writhing and squirming, and will feast
on its green entrails.
“The carabid, which is also a passionate lover of game, has the
calosoma’s activity and brilliance, but is of smaller size. Some are
bronze in color, others golden, still others of a copper tint, or black
edged with a superb violet. All explore with keen scrutiny the thick
tufts of grass, and give chase to small prey such as larvæ,
caterpillars, and worms. The most common example of this class wears a
golden green coat and is a frequenter of gardens, where it makes war on
all kinds of vermin. It is the little guardian of our beds of peas and
beans, and of our flower borders. In honor of its services to the
garden we call it the gardener.
“The calosoma and the carabid do not fly; they are made for running, as
is evident from their long legs, their agile movements, and their lithe
form. They chase the game in hot pursuit, or else lie in wait for it
behind a leaf, but never pursue it on the wing. On the other hand, the
scarab, the common June-bug, and a host of other insects fly very
well.”
“But why don’t they all fly?” asked Emile.
“I will tell you,” replied his uncle. “Look carefully at the June-bug a
moment. It has two kinds of wings: on the outside two large and
substantial scales of horn, and beneath these two fine membranous
wings, expanded during flight, but carefully folded together and
concealed when not in use. The outside scales are called elytra, or
sheaths. They serve as a case for enclosing and protecting the delicate
membranous wings, which alone are fitted for flying. The carabid and
the calosoma have sheaths of splendid brilliance, it is true, but
beneath these sheaths there are no membranous wings to spread
themselves in flight and fold up again in repose. Hence these two
insects are unable to fly.
“The dytiscus and the hydrophile, whose names signify ‘diver’ and
‘water-lover’ respectively, both frequent the waters of deep ponds, of
ditches, and of pools. With their legs flattened out like oars, their
very smooth bodies, arched above and keel-shaped below, they are
first-rate swimmers and divers. It is a feast for the eye to follow the
graceful agility of their oars when they row calmly on the surface or
plunge beneath it.
“At the least alarm they dart quickly to the bed of the pond and take
refuge amid the water plants. On the instant of diving their belly is
seen to flash like a plate of polished silver. The reason of this
borrowed sheen is found in a thin layer of air that they carry with
them adherent to the belly. With this supply they will have air to
breathe until, all danger past, they ascend again to the surface.
“In the matter of costume these two master-swimmers are of modest
appearance. Both are of a very somber olive green, but in addition the
dytiscus wears faded gold lace on its sheaths. If the pond dries up or
ceases to please them, they can quickly betake themselves to
another—not on foot, for their flattened legs, excellent as oars, are
worthless in walking, but by flight, with the help of their membranous
wings, ordinarily hidden under the sheaths, where the water cannot
reach them.
“In old oak trees the larva of the capricorn-beetle, another ravager of
forests, leads much the same kind of life as does the grub of the
stag-beetle. Large in size, all black with gleams of chestnut, this
insect is remarkable for its jointed horns, which are longer than its
body. What can it do with these cumbersome ornaments? Does it wear them
on its forehead to intimidate the foe? I would not venture to dispute
the matter, but what I do know very well is that with its extravagantly
long horns it frightens the inexperienced young pupil so that he dares
not touch it, and he calls it the devil. All the same, the
capricorn-beetle does not deserve the evil reputation it has got from
the timid. It is perfectly harmless.
“Insects’ horns are called antennæ. All have them, some longer and some
shorter, now of one shape, now of another. In some instances they are
flexible filaments, jointed chaplets; in others, short stems ending in
either a cluster of little buds or a bunch of leaves pressed one
against the other. See for example the burly and magnificent insect
that browses the foliage of our pine-trees on warm summer days. It is
called the pine-beetle. On a chestnut background it wears a sprinkling
of white spots. The antennæ carry at the end a set of little plates or
scales which open and shut like the leaves of a book.
“It is in place here to mention the common June-bug, furnished like the
pine-beetle with antennæ bearing leaf-clusters at the end. I propose to
tell you its story in detail; for, if this little creature is the joy
of young people of your age, it is also the terror of the farmer.
“But first one word more to conclude our short story of sheath-winged
insects. Their number is immense. Nearly all have membranous wings
under the protecting case formed by the sheaths; and these can fly.
Others, relatively few, are unprovided with membranous wings, and hence
are unfitted for flight. This entire group bears the general name of
coleoptera, meaning sheath-winged. A coleopter is any insect furnished
with sheaths, whether it flies or not.”