THE EUPLOEINAE
So far as the great majority of readers are concerned, this subfamily includes but one species—Anosia plexippus, the familiar Monarch or Milkweed butterfly, which is common every summer in every state in the Union. The main color of the wings is bright reddish brown, but the edges are black, and there are some white spots in the black area, particularly in the fore wings. The pale green eggs are laid upon the milkweed, and soon hatch into little black and white caterpillars. The mature caterpillar is greenish yellow with black bands, and each end of the body bears a pair of slender black “horns” or filaments. The stout chrysalis is green with golden markings. This butterfly has a bitter taste, and so is not molested by birds or insectivorous mammals. For this reason Anosia plexippus has become very abundant and spread over a vast territory. Other butterflies which happen to resemble it share in this protection even though they have no disagreeable flavor, and this has given rise to the phenomena of mimicry, which is discussed elsewhere in this book. Another interesting thing about the Monarch is the fact that it does not hibernate in any stage; the eggs, caterpillars, and chrysalids die when the cold weather overtakes them, while the adults gather in great swarms and migrate southward, where they breed continuously throughout the winter. With the advent of warm weather the young southern Monarchs come north, deposit their eggs on northern milkweed, and the cycle begins again.
Fig. III.—The Silver-Spotted Skipper (Epargyreus tityrus), a typical Hesperid. A, egg; B, mature caterpillar; C, pupa or chrysalis; D, imago.