Insects feed voraciously on leaves, vegetables, fruit, on human blood--sad to relate--and fortunately on one another. Mosquitoes, thank Heaven, have parasites that cling to the delicate rings of their bodies, stinging the arch-stinger, and inflicting by their venomous bites the same agonies the sufferers inflict on others. It is to be hoped those gentlemen will increase and multiply, and after exterminating mosquitoes may pay their addresses to the black gnats. Certain families, especially of the _coleoptera_, emit a species of phosphorescent light in the dark, occasionally light enough to read by. The majority of insects have wings, but many have not, and in some only one gender is winged. A few kinds, such as the locusts, katydids, crickets, death-ticks, emit sounds, to which man’s sympathies have added either a pleasant or painful association, and produce these peculiar cries generally by rubbing the wings or some part of the body. The wings of insects do not exceed four, and are often limited to two; their legs are six; some have antennæ or feelers, others long whisks from their tails.
The _neuroptera_, or net-winged insects, _florfliegen_, gauze-flies, as they are called by the Germans, include the principal pets of the fly-fisher. Their bodies are long, tapering and delicate; their wings, four, almost transparent and marked with net-like veins. They keep in continual motion for the purpose of catching smaller insects, on which they mainly feed, and generally deposit their eggs in the water, where the grubs live from one to two years on plants or other insects.
That most fearful looking, but really harmless and beneficent creature, the devil’s darning-needle, or dragon-fly, _libellula_, is a remarkable specimen of this family. They are called _demoiselles_ by the French, _wasserjunfern_, water-virgins by the Germans; but, in spite of these pretty appellations, are the tyrants of the surface of the ponds; they seize and tear to pieces all other insects, including butterflies and mosquitoes, and will clear a house of the common fly. They are cruel, rapacious and insatiable, and I do not know of their ever being used as bait for trout.
The _phryganea_, or water-moth, is one of the favorites of the fly-fisher. Its grubs surround themselves with a case formed of wood or grass, and are used by him as bait under the name of caddis-worms. They are the favorite food of the trout in early spring. But the _ephemeridæ_ include most of the specimens imitated by the fisherman. The larvæ of these live in the water, for one or more years, and then, swimming to the surface, suddenly change into winged insects, delicate and beautiful. They sometimes appear in myriads, their dead bodies covering the water. A few make a second change after flying about for a time, and crawl out of their skins once more, leaving their old clothes, to all appearance perfect, sticking to a tree or fence. On their first appearance they are said to be in the _pseudimago_ state, and to them the name duns is applied by the fly-fisher; when they change to the _imago_ or perfect fly, they are called piscatorially spinners. There are exceptions to this uniformity, as with the May-flies; the green drake is the _pseudimago_, and the grey drake the _imago_.