Butterflies - The Tribe Of The Fritillaries
( Originally Published 1917 )
This is one of the most distinctive tribes of the family of Nymphs. The clubs of the antennae are about twice as long as broad and curiously spoon-shaped, The palpi are large and bushy, with the last joint very short. Most of the species are rather large and practically all are beautifully mottled in various tones of brown, red, black, and silvery gray. A large proportion of our midsummer butterflies are members of this tribe.
The Gulf Fritillary
In tropical America there is a genus of butterflies called Agraulis. These are fairly large insects, approximating the size of the Viceroy, which show most beautiful colors in the tropical sunshine. One member of this genus has come north to our Southern states, and is occasionally found as far up as Virginia and southern Illinois, extending below this from ocean to ocean. It reveals on its upper surface the most exquisite tints of iridescent purples and browns, suggesting by its form and color as thus seen a tropical species. The lower wing surface, when the wings are closed in their natural position, shows only a spangled effect of silver-white and brown, which is very suggestive of the under surface of our northern Spangled Fritillaries. So this beautiful species may fittingly be called the Gulf Fritillary, carrying over from the north some of its peculiar beauty and connecting with the equally distinctive beauty of the tropical south.
Like so many other southern butterflies the eggs of this species are laid upon the leaves of passion vines. The caterpillars develop very rapidly and when matured are yellowish or brownish yellow, striped with darker lines along the back and sides. There are black branching spines, arranged in rows beginning on the head and running backward on the body. The whole cycle of life from egg to butterfly may take place within the short period of a month and one brood succeeds another in so irregular and rapid a fashion that it is difficult to determine definitely the number of broods in a season.
The Variegated Fritillary
There is something in the appearance of the upper surface of this butterfly that suggests the other Fritillaries on the one hand and the Emperors on the other. The coloring and marking is a bit like the former and the shape of the wings like the latter. The general color is a golden brown with darker markings arranged m bands and eye-spots in a rather complicated pattern. The under surface, so far as it is exposed when the butterfly is at rest, is a beautiful marbled combination of gray and brown which is probably distinctly obliterative in the haunts of these insects. The front wings have the outer margin concave in the middle, giving a special prominence to the shape of each front outer angle.
This butterfly is a southern rather than a northern species, but it is found occasionally from Montana to Massachusetts and southward to Arizona, Mexico, and Florida. Even in northern Indiana it is very seldom found and is considered rare in the southern part of that state. Around Buffalo, New York, it is also rare and is not common in the vicinity of New York City. In the more Southern states, however, it is abundant and extends well through the continent of South America.
There is considerable evidence to indicate that this butterfly hibernates as an adult. In the more southern regions it probably also hibernates in other stages, especially the chrysalis and the larva. In regions where it is double-brooded, as it appears to be in the latitude of New York City, the seasonal history seems to run some-thing like this: the partly grown caterpillars which have passed the winter in shelter at the surface of the soil feed upon the leaves of violets and certain other plants. They change to chrysalids, probably in May, and emerge as butterflies in June. These butterflies lay eggs for a summer brood of caterpillars which may feed upon the leaves of violets, May apples, portulaca, and stonecrop. They grow into cylindrical worms of a general reddish yellow color, marked by longitudinal stripes of brown upon the sides and a row of whitish dots upon the back. They become matured in time to disclose the butterflies of the second brood in August and September. Presumably these butterflies lay eggs that develop into caterpillars which hibernate when partially grown.
Farther south there are probably three broods a year and hibernation may take place in various stages. There is good opportunity for careful work in determining the life-history of the species in different latitudes. The butterfly is found in much the same situations as the other Fritillaries, flying over meadows and along the borders of woods.
The Diana Fritillary
This magnificent butterfly differs from the other Fritillaries in the fact that the females are so unlike the males that only a skilled naturalist would even guess that they are related. Both sexes are rather rare and are found only in a comparatively narrow range extending from West Virginia to Missouri, northward to Ohio and Indiana, and southward to Georgia and Arkansas.
This species was first described by Cramer a long time ago from specimens of the male sex. It was later described by Say and other writers all of whom saw only the males. The other sex was first recognized by William H. Edwards, whose account of its discovery as given in his splendid work on the Butterflies of North America is worth quoting:
"No mention is made of the female by any author," wrote Mr. Edwards, "and it seems to have been unknown till its discovery by me in 1864 in Kanawha County, West Virginia. On the 20th August, I saw, for the first time, a male hovering about the flowers of the iron-weed (Vernonia fasciculata), and succeeded in taking it. Two days afterwards, in same vicinity, while breaking my way through a dense thicket of the same weed, hoping to find another Diana, I came suddenly upon a large black and blue butterfly feeding so quietly as to allow me to stand near it some seconds and watch its motions. It seemed to be a new species of Limenitis, allied to Ursula, which it resembled in color. But on taking it, I saw it was a female Argynnis, and the general pattern of the under wing left little doubt of its affinity to the Diana male, despite its total difference in color and of upper surface. Subsequent captures confirmed this conjecture, and out of the large number that have since been taken the males have been of the known type and the females black, with no tendency in either to vary in the direction of the other.
"When my attention was called to the species I found it not very uncommon, always upon or near the iron-weed, which is very abundant and grows in rank luxuriance upon the rich bottom lands of the Kanawha River, frequently reaching a height from eight to ten feet and in August covered by heads of purple flowers that possess a remarkable attraction for most butterflies. Both sexes are conspicuous, the males from the strong contrast of color and the females from their great size and the habit of alighting on the topmost flower and resting with wings erect and motionless. It is an exceedingly alert and wary species, differing in this from our other Argynnids. At the slightest alarm it will fly high into the woods near which, upon the narrow bottoms or river slopes, it is invariably found. It is a true southern species, sensitive to cold, not to be looked for in the cooler part of morning but flying down from the forest when the s is well up. From eleven to three o'clock is its feeding time."
The life-history of this fine butterfly is similar to that of the lesser Fritillaries. The butterflies appear from mid-summer onward, the males preceding the females, and the eggs are laid on or near violets in August or September. The larvae hibernate and mature early the following summer. As they approach the chrysalis stage they are rather large velvety black caterpillars with brown heads and rows of fleshy barbed spines that show an orange tint at their bases. There is thus but one generation each year.
The Regal Fritillary
The Regal Fritillary, fresh from the chrysalis, still showing the marvelous sheen of its iridescence, furnishes one of the most beautiful exhibitions of color in the world of nature. Over the whole wing surface there are tiny scales that reflect the sunlight in an almost dazzling manner, giving a distinct purplish tone especially to the hind wings. The Regal Fritillary is one of the largest butterflies a the distinctive group to which it belongs. The wings expand some three inches and the rather thick body is more than an inch long. The general ground color of the wings is brown, with distinct markings of blackish which in the hind wings almost obscure the brown. On each of the latter as seen from above there is a distinct row of cream-colored spots across the middle, duplicated by a similar row of brown spots near the margin. The under surface of both pairs of wings is much lighter and thickly mottled all over with light cream-colored spots of a large size and more or less triangular shape. (See frontispiece.
Like the other Argynnids, the Regal Fritillary is single-brooded during the year and it has a rather remarkable longevity in each stage of its life. The newly hatched caterpillars go into hibernation and live through the winter without feeding, finding shelter at the surface of the ground, especially beneath the leaves of violets which form their chosen food plants. When the snow has disappeared and the warmth of the spring sun brings them out of their winter lethargy these tiny caterpillars feed upon the violet leaves and grow slowly for several weeks. They then change to chrysalides, the time for doing this varying considerably with the individual and doubtless with the warmth of the situation in which each is living. The length of time spent in the chrysalis varies also, but in general it seems to be less for those which develop into male butterflies than for the females. It is a curious fact that the former may be found for nearly two weeks before any of the latter appear.
The first butterflies of this species are usually disclosed rom the chrysalis late in June or early in July. They continue to come forth for several weeks, apparently until nearly the middle of August. They lead a leisurely life, visiting freely the flowers of goldenrod, iron weed, boneset, Joe Pye weed, and especially swamp milkweed. They are most likely to be found in lowlands and along the borders of swamps where these favorite flowers are growing. It evidently requires some time for the eggs to develop within the ovaries, for the butterfly cannot be.-gin laying these until the latter part of August. They apparently are normally deposited on the under side of violet leaves, although so far as I know no butterfly has been seen thus laying her eggs. It would be an interesting point for some young observer to determine. Even the eggs take a long time to develop, not hatching for three or four weeks after they are laid. When they do hatch the tiny caterpillars seem not to eat at all but to go diectly into hibernation.
These butterflies are to be found in their preferred habitats almost any time during July, August, and September. Apparently many of them live as adults for nearly three months so that whether we consider the egg, the larva, the chrysalis, or the adult we have in this species an unusual duration of life. This is doubtless an adaptation to the fact that the species must get through the year with only one brood.
This unity of habit with no such variations as occur in any butterflies with a wider range north and south is apparently correlated with the distribution of this butterfly. It is found in a belt of territory running from New England and the Atlantic states westward at least to Nebraska along a line which approximates the annual isotherm of fifty degrees Fahrenheit.
The Great Spangled Fritillary
To one who wanders much in the woods and open fields there are few summer scenes more characteristic of the season than that of a group of milkweeds in full flower, surrounded by a host of brown butterflies busily sucking the nectar from the curious pink blossoms. There are likely to be several species of these winged creatures, but in many regions of America the largest and most conspicuous will generally be the Great Spangled Fritillary butterfly is easily recognized by its large size and its combination of two colors of brown, with whitish or silverish spots scattered over the lower surface of the wings.
The life-history of this insect is of peculiar. interest on account of the way in which it passes the winter. The mother butterfly remains upon the wing through many weeks in summer, so that toward the end of August or early September a large proportion of the specimens have a decidedly frayed appearance. They are patiently waiting for the season of the year when they can deposit their eggs, apparently knowing by instinct that this must not be done until early autumn. When the proper season arrives they lay their eggs upon the leaves or stems of wild violets, apparently without much reference to the particular species. Sometimes they have been reported simply to drop the eggs loosely upon the violet plant with no attempt to fasten them in place. Having thus deposited the eggs the mother butterflies soon die.
It would not seem strange if these eggs remained unhatched until the following spring, but the fact is that the eggs hatch very soon into small caterpillars that eat off part of the shells in order to escape and sometimes eat also part of the shell remaining after they have emerged. Various good observers have apparently established the fact that these tiny caterpillars eat nothing else before winter sets in. It seems curious indeed that they should not nibble at the leaves or stems of the violet plants in order to be slightly prepared for the long fast that awaits them before they will find food upon the young buds the following spring. The case is somewhat similar to that of the common tent caterpillar which becomes a fully formed caterpillar within the egg shell before the end of autumn, but remains unhatched until the following spring. In the present case the caterpillar hibernates outside of the egg shell rather than within it.
When at Iast the warm sunshine of spring starts the violets into new growth the tiny caterpillars begin feeding upon the succulent tissues. They nibble away day after day for a week or more before they become so large that they have to cast their skin for the first time. They then feed again and continue this process of feeding and moulting until early in summer. They are likely to bide them-selves during daylight and have the reputation of being difficult to rear under artificial conditions.
The full-grown caterpillar wanders along the surface of the ground in search of suitable shelter for the chrysalis period. When it comes to a large stone with sides projecting more or less horizontally or a log lying upon the ground or even a large piece of loose bark it is likely to stop and change to the pupa or chrysalis. In this condition it is dark brown in color and well covered with thickened tubercles, especially along the back of the abdomen.
About a fortnight later the chrysalis breaks open and the fully developed butterfly comes forth. ft rests quietly for a time while its wings expand and the tissues harden and then sallies forth for its long period of flight; for this insect is single-brooded in the Northern states at least and the butterflies that thus mature late in June or early in July are likely to remain alive until early in September. So they have a comparatively long life for a butterfly that does not hibernate as an adult.
The Silver-spot Fritillary
Our brown Fritillaries are seldom found without several species mingling together. This is not strange, for they have similar habits throughout their entire lives. So when you see a bevy of butterflies collected around the midsummer blossoms of the milkweed, you are pretty sure to find that the Great Spangled Fritillary is associated with the Silver-spot and probably one or two other related forms. The Silver-spot is generally decidedly smaller than the one first named and the surest way to be certain of it is to look on the under side of the hind wing and see whether there is a broad band of buff between the two outer rows of silver spots. If this band has disappeared or is nearly all taken up by the brown ground color of the wing, you may be pretty sure we have the Silver-spot Fritillary.
When one has firmly fixed in mind the life cycle of one of these butterflies, one has a model after which to fashion the rest, for our several species are remarkably alike in this respect.
The Silver-spots are on the wing for several weeks in summer. During the latter part of this time the females lay eggs upon violet leaves. These eggs shortly hatch into caterpillars that go directly into hibernation, taking no. food before winter sets in. The following spring they feed upon violet leaves and mature in time to change to chrysalids and emerge as butterflies in early summer. There is but one brood a year and the species is widely distributed over southern Canada and the Northern states. It emends south to Virginia and Pennsylvania and west to Nebraska, Montana, and Washington.