“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 [[239]]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 [[240]]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 [[241]]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.” [[242]]