Fig. 238.—Hawk moth, a rapid flyer.
Fig. 239.—Death's-head moth.
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.
Fig. 240.—Pupa of butterfly.
Fig. 241.—Basketlike cocoon of a South American moth.
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.
