Indeed, one of our most splendid butterflies is the Anosia plexippus, otherwise known as the milkweed butterfly, rightly named also the monarch. Every boy who knows the country in summer knows him by his rich, red coloration, his strong, black-bordered wings with their black veins. Every bird knows him too and lets him alone. On the first median nervule of the hind wings of the butterfly is a scent bag whence he dispenses an odor so disagreeable to the bird who would eat him that he goes free, and is not afterward troubled.
Every boy who knows the country in summer knows him by
his rich, red coloration, his strong, black-bordered wings
with their black veins
Along with the monarch sipping honey with eager industry from the meadow milkweed, you will often see the viceroy, who, as a viceroy should, closely imitates, but does not equal, the monarch. He has neither the monarch’s vigor of flight nor his means of defence from predatory birds, but his safety—so the students tell us—lies in looking so much like his superior that he also is let alone. The students go on to say that his is a good example of the imitative power of insects whereby they escape destruction by seeming to the casual eye to be something else.
The viceroy, which is a Basilarchia disippus, thus looks not the least like other members of his family, but consciously mimics the coloring of the monarch for safety. Thus many tropical beetles contrive to look like wasps that they may not be molested, and some insects look like brown leaves and others like green ones.
But do they contrive, imitate, mimic? It is no doubt true that because of the resemblance they escape, but to say that they imitate or contrive or mimic seems to me to be to assume a knowledge of the workings of the inner consciousness of an insect that not even the most careful student can have. I am more inclined to believe that the so-called mimics are fortunate in an accidental resemblance and so escape the destruction of their species which has fallen upon many a less fortunate type.
Yet no butterfly, however exquisite his coloring, or however strong and graceful his flight, twangs with his fluttering wings the fine heartstrings of romance as does the monarch. The first one that came dancing down the sunlight to the sweet rocket in bloom in my garden this spring brought to me a spicy odor of tropic isles. The beating of his wings shed, as he passed, faint fragrance of Mexican jasmine, and I thought I saw slip from them the infinitesimal dust of the pollen of stephanotis lately blooming in the glades of Panama. Three months before he floated serenely beneath my cherry tree he may well have soared through the tropic glades where crumble the ruins of the palaces of the Incas.
His flight, seemingly as frail as that of a red autumn leaf sliding down the October zephyr to carpet the nearby field with rustling fragrance, has matched that of that rifle-ball of bird life, the ruby-throated humming-bird. Together they sip the sweets of my sweet rocket in the spring. Together they wing their way south to the region of perpetual summer when the winds of late September promise frost. Sometimes in this annual flight the monarchs pass the sandy stretches of the New Jersey coast in swarms that, stopping at nightfall for rest, refoliate with their folded wings the shrubs left bare by the autumn gales.
It may be that, like the birds, the knowledge of the route they must follow is bred in the marrow of their butterfly bones by the constant use of a million generations. It may be that they simply drift away from the cool wind from the North toward the Southern sun that shines so serenely in the bright autumn days. But whether through the guiding hand of Providence, or inherited wisdom, or a fortunate tact that acting from day to day produces the happy result, this Southern movement in winter is the sole salvation of the species here in the North.
If they did not make these long flights we should have no Anosias with us each summer, for unlike other butterflies the frost kills them in whatever form they remain to brave it. All summer long their long, red wings bear them bravely from one clump of milkweed to another. They sip the honey which each floret of the umbels holds forth, the sticky mass the size of a pinhead. They lay their eggs upon its leaves and the black and yellow caterpillars hatch and feed there. Then they hang in a green and gold chrysalis from a nearby twig till the imago, the perfect butterfly, bursts its bonds and sails away to find more milkweed. There may be several broods of a summer, but the frost stops all that. The monarch may not winter here, nor may his eggs or chrysalids survive the cold.