The Monarch Butterfly

Teacher's Story

T IS a great advantage to an insect to have the bird problem eliminated, and the monarch butterfly enjoys this advantage to the utmost. Its method of flight proclaims it, for it drifts about in a lazy, leisurely manner, its glowing red making it like a gleaming jewel in the air, a very different flight indeed from the zigzag dodging movements of other butterflies. The monarch has an interesting race history. It is a native of tropic America, and has probably learned through some race instinct, that by following its food plant north with the opening season, it gains immunity from special enemies other than birds, which attack it in some stage in its native haunts. Each mother butterfly follows the spring northward as it advances, as far as she finds the milkweed sprouted. There she deposits her eggs, from which hatch individuals which carry on the migration as far to the north as possible. It usually arrives in New York State early in July. As cold weather approaches, the monarchs often gather in large flocks and move back to the South. How they find their way we cannot understand, since there are among them none of the individuals which pressed northward early in the season.

The monarch butterfly.

The very brilliant copper-red color of the upper sides of the wings of the monarch is made even more brilliant by the contrasting black markings which outline the veins and border the wings, and also cover the tips of the front wings with a triangular patch; this latter seems to be an especially planned background for showing off the pale orange and white dots set within it. There are white dots set, two pairs in two rows, between each two veins in the black margin of the wings; and the fringe at the edge of the wings shows corresponding white markings. The hind wings and the front portions of the front wings have, on their lower sides, a ground color of pale yellow, which makes the insect less conspicuous when it alights and folds its wings above its back, upper surfaces together. The black veins, on the lower surface of the hind wings, are outlined with white, and the white spots are much larger than on the upper surface. The body is black, ornamented with a few pairs of white spots above and with many large white dots below. The chief distinguishing characteristic of insects, is the presence of six legs; but in this butterfly, the front legs are so small that they scarcely look like legs.

The viceroy butterfly.  Note the black band on the hind wings which distinguishes it from the monarch, which it imitates in color and markings.

It is easy to observe the long, coiled tongue of the butterfly. If the act is done gently, the tongue may be uncoiled by lifting it out with a pin. To see a butterfly feeding upon nectar, is a very interesting process and may be observed in the garden almost any day. I have also observed it indoors, by bringing in petunias and nasturtiums for my imprisoned butterflies, but they are not so likely to eat when in confinement. The antennæ are about two-thirds as long as the body and each ends in a long knob; this knob, in some form, is what distinguishes the antennæ of the butterflies from those of moths. The male monarch has a black spot upon one of the veins of the hind wing; this is a perfume pocket and is filled with what are called scent scales; these are scales of peculiar shape which cover the wing at this place and give forth an odor, which we with our coarse sense of smell cannot perceive; but the lady monarch is attracted by this odor. The male monarch may be described to the children, as a dandy carrying a perfume pocket to attract his sweetheart.

The scales on a butterfly's wing, as seen through a microscope.

It is very interesting to the pupils if they are able to see a bit of the butterfly's wing through a three-fourths objective; the covering of scales, arranged in such perfect rows, is very beautiful and also very wonderful. The children know that they get dust upon their fingers from butterflies' wings, and they should know that each grain of this dust is an exquisite scale with notched edges and a ribbed surface.

The monarch is, for some reason unknown to us, distasteful to birds, and its brilliant colors are an advertisement to all birds of discretion, that here is an insect which tastes most disagreeably and that, therefore, should be left severely alone, There is another butterfly called the viceroy, which has taken advantage of this immunity from bird attack on the part of the monarch and has imitated its colors in a truly remarkable way, differing from it only in being smaller in size and having a black band across the middle of the hind wing. (See The Ways of the Six Footed, "A Sheep in Wolf's Clothing").

The monarch caterpillar.  Photo by M. V. Slingerland.

The milkweed caterpillar, which is the young of the monarch butterfly, is a striking object, and when fully grown is about two inches long. The milkweed is a succulent food and the caterpillar may mature in eleven days; it is a gay creature, with ground color of green and cross stripes of yellow and black. On top of the second segment, back of the head, are two long, slender whiplash-like organs, and on the seventh segment of the abdomen is a similar pair. When the caterpillar is frightened, the whiplashes at the front of the body twitch excitedly; when it walks, they move back and forth. Those at the rear of the body are more quiet and not so expressive of caterpillar emotions. These filaments are undoubtedly of use in frightening away the little parasitic flies, that lay their eggs upon the backs of caterpillars; these eggs hatch into little grubs that feed upon the internal fatty portions of the caterpillar and bring about its death through weakness. I remember well when I was a child, the creepy feeling with which I beheld these black and yellow-ringed caterpillars waving and lashing their whips back and forth after I had disturbed them; if the ichneumon flies were as frightened as I, the caterpillars were surely safe.

Monarch chrysalis. A jewel of living jade and gold.

The caterpillar will feed upon no plant except milkweed; it feeds both day and night, with intervals of rest, and when resting, hides beneath the leaf. Its striking colors undoubtedly defend it from birds, because it is as distasteful to them as is the butterfly. However, when frightened, these caterpillars fall to the ground where their stripes make them very inconspicuous among the grass and thus perhaps save them from the attack of animals less fastidious than birds. These caterpillars, like all others, grow by shedding the skeleton skin as often as it becomes too tight.

The monarch chrysalis is, I maintain, the most beautiful gem in Nature's jewel casket; it is an oblong jewel of jade, darker at the upper end and shading to the most exquisite whitish green below; outlining this lower paler portion are shining flecks of gold. If we look at these gold flecks with a lens, we cannot but believe that they are bits of polished gold-foil. There may be other gold dots also, and outlining the apex of the jewel, is a band of gold with a dotted lower edge of jet; and the knob at the top, to which the silk which suspends the chrysalis is fastened, is also jet. The chrysalis changes to a darker blue-green after two days, and black dots appear in the gold garniture. As this chrysalis is usually hung to the under side of a fence rail or overhanging rock, or to a leaf, it is usually surrounded by green vegetation, so that its green color protects it from prying eyes. Yet it is hardly from birds that it hides; perhaps its little gilt buttons are a hint to birds that this jewel is not palatable. As it nears the time for the butterfly to emerge, the chrysalis changes to a duller and darker hue. The butterfly emerges about twelve days after the change to a chrysalis.

The winter home of the viceroy caterpillar.

References—Every Day Butterflies, Scudder; How to Know the Butterflies, Comstock; Moths and Butterflies, Dickerson; Ways of the Six Footed, Comstock; Moths and Butterflies, Ballard.

The male monarch butterfly, showing the scent pockets on the hind wings.  Photo by M. V. Slingerland.

Method—This lesson should be given in September, while yet the caterpillars of the monarch may be found feeding upon milkweed, and while there are yet many specimens of this gorgeous butterfly to be seen. The caterpillars may be brought in, on the food plant, and their habits and performances studied in the schoolroom; but care should be taken not to have the atmosphere too dry.

2. Is the flight of the monarch rapid or slow and leisurely? Is it a very showy insect when flying? Are its colors more brilliant in the sunshine when it is flying than at any other time? Why is it not afraid of birds?

3. When the butterfly alights, how does it hold its wings? Do you think it is as conspicuous when its wings are folded as when they are open?

4. Can you see the butterfly's tongue? Describe the antennæ. How do they differ from the antennæ of moths? How many legs has this butterfly? How does this differ from other insects? Note if you can see any indications of front legs.

5. Is there on the butterfly you are studying, a black spot near one of the veins on each hind wing? Do you know what this is? What is it for?

6. Why are the striking colors of this butterfly a great advantage to it? Do you know of any other butterfly which imitates it and thus gains an advantage?

3. How many whip-lash shaped filaments do you find on the caterpillar? On which segments are they situated? Do these move when the caterpillar walks or when it is disturbed? Of what use are they to the caterpillar?

4. Do you think this caterpillar would feed upon anything except milkweed? Does it rest, when not feeding, upon the upper or the lower surface of the leaves? Does it feed during the night as well as the day?

5. If disturbed, what does the caterpillar do? When it falls down among the grass how do its cross stripes protect it from observation?

6. Tell all the interesting things which you have seen this caterpillar do.

3. To what is the chrysalis attached? Is it in a position where it does not attract attention? How is it attached to the object?

4. After three or four days, how does the chrysalis change in color? Observe, if you can, the butterfly come out from the chrysalis, noting the following points: Where does the chrysalis skin open? How does the butterfly look when it first comes out? How does it act for the first two or three hours? How does the empty chrysalis skin look?