Of all the insects the butterflies (Fig. 229) are the most beautiful. Nature has arrayed them in coats of many colors. Every tint and every possible shade of color, including metallic, is found among them. In some of the South American forests they are of gigantic size, a blaze of iridescent blue, as though formed of the most delicate flakes of that beautiful mineral labradorite.

The butterflies add to the beauty of nature. Among the trees they congregate, forming dashes of color, red, blue, green, and golden yellow. They vie with the flowers in their splendors; besides being ornamental they accomplish a great work in carrying pollen from flower to flower and from plant to plant. They have small heads (Fig. 230), short antennÆ, and four beautiful wings which are covered with minute scales. Each of the latter when examined under a microscope becomes a resplendent object, glistening like the plate of some gorgeous armor. The mouth parts are adapted for sucking, and are coiled up when not in use (Fig. 231). They consist of two tubular or hollow threads.

The ordinary caterpillar is the larva of the butterfly. The eggs are deposited on leaves and various places, and soon hatch into caterpillars (Fig. 232). These lead a predatory life for some time, doing a vast amount of damage, almost every plant having its peculiar pest. Some affect one tree, some another. The famous elm trees of many of the New England cities have more than once been threatened by these larvÆ. They shed their coats several times. The caterpillar finally merges into the chrysalis, from which it escapes as the perfect insect. All of these changes can easily be observed by keeping a caterpillar under continuous observation. The butterflies have well-developed legs, but they rarely use them for locomotion, preferring to fly from flower to flower. The tortoise-shell butterfly is a familiar form (Fig. 233), its marvelous colors resembling this shell. Some have an under covering of pure silver. Another conspicuous form is the white butterfly (Fig. 234), which, as its name suggests, is pure white, with several black spots.

When the butterfly is at rest its wings are held aloft, and many are so colored that in this position the wing resembles a leaf and the animal escapes observation. A marvelous example of this protective mimicry is observed in the East Indian butterfly, Kallima (Fig. 235). The wings have a little projection which resembles a stem from which a dark mark resembling a midrib extends. When the butterfly alights, this seeming stem, as shown in the illustration, appears to join to the branch, and the resemblance to a leaf is so perfect that the most careful observer is often deceived. Other butterflies observed by Wallace mimicked dry oak leaves and dead leaves of various kinds. All the spots and colors of decay were imitated in their wings. Other Indian forms resemble fungus, and utterly disappear as they alight upon it. No more attractive butterfly is seen than the finely marked Vanessa, the peacock butterfly (Fig. 236), which has beautiful peacock marks upon its wings in vivid blue.

In southern California, almost every spring, there is a migration of butterflies from the south northward along the Sierra Madre. I have watched them for hours, numbers being seen over a given spot every moment. By writing to postmasters and other persons in different sections, I found that the migrating band was two hundred miles long and from ten to twenty miles wide. Doubtless this was but a fraction of its actual extent, it being made up, in reality, of millions of yellow butterflies. Darwin saw such a migration in South America. Their pathway was several miles in width, they filled the air like a yellow cloud, and were several hours passing a given point. Vessels out at sea have met with similar flocks blown away from the shore.

The butterflies are included in the Lepidoptera, and are the day-flying forms. There are many other insects equally beautiful, in more subdued tints, which are night flyers. These are the moths (Fig. 237), which are slow of flight, ponderous, and have extraordinary tongues for sucking the juices from the flowers. They can be distinguished from the butterflies by their feathered antennÆ. One of the best known for its ravages is the dwarf moth, the worm of which plays such havoc among woolens. The cankerworm moth is equally a pest among valuable shade trees. Another familiar form is the hawk moth (Fig. 238), which so resembles a humming bird in appearance and motion that it is almost impossible to distinguish between the two, the moth being one of the most active, poising over flowers and inserting its enormous tongue to secure the sweets there concealed. A showy moth is the huge Attacus, its larva being especially large and voracious.

The moths display as great a variety in their shapes, colors, and sizes as the butterflies. The death's-head moth (Fig. 239) is perhaps as startling as any, bearing on its back a well-defined figure of a skull. The most valuable moth to man is the silkworm moth, the wings of which have a spread of six inches and are a brilliant ochre yellow, fawn, or mouse color, marked with striking peacock-like eyes. They deposit eggs, but the development of the caterpillar is somewhat different from that of the butterfly larva. The latter passes its pupa stage as an unprotected chrysalis attached to some object by the tail (Fig. 240), but the caterpillar of the moth secretes silk from a gland in its head, and with this forms about itself a cocoon. This is unwound by machinery and woven into the valuable silk of commerce. The silk industry brings to the weavers of the United States alone an annual sum amounting to about $30,000,000. The silkworm can easily be kept and all its changes watched, and many persons are interested in rearing the worms. The time required by the worm to form its silk cocoon varies with the locality. Thus in France it will complete it in four days, while in England forty or more days are necessary. About two hundred cocoons weigh a pound.

Silkworm moths are ravenous eaters, living principally on mulberry leaves. They show much intelligence in forming their cocoons. Thus a South American moth (Fig. 241) forms a basketlike structure which it suspends from some limb. The cradle swings in the wind like a seed pod, more than anything else, and would never be suspected as inclosing a living creature. Many of the moths, by some remarkable instinct, deposit their eggs where the young will find an immediate supply of food. This care for their young is the cause of a vast amount of damage among fruit trees. The fruit moth, as an example, deposits its eggs in fruit; the caterpillar penetrates it and devours the interior, thousands of bushels of apples being destroyed yearly in this way, not to speak of other fruits.