The Painted BeautyVanessa hunteraOne of the most interesting phases of the study of butterflies is to learn how often they take advantage in their life-history of any peculiarity of the food plant which hasa protective value. The Painted Beauty is an excellent illustration of this. The caterpillar feeds upon the leaves of the common Everlasting or Gnaphalium. This is an abundant and widely distributed plant, found along roadsides and in fields and pastures. It is notable for the woolly covering on stems, leaves, and flowers—this dry, hairy surface being so evident that the flowers will apparently continue in blossom when they have dried, hence its common name Everlasting or, as the French call a similar flower, Immortelle. (See plate,page 161.)The utilization of the hairs upon the leaves is begun by the mother butterfly when she lays her egg upon the upper surface, pushing it down among the hairs so that it is almost concealed. Should you be fortunate enough to find one of these eggs you would see that it is a small, yellowish green object, looking like a tiny barrel with several vertical ribs upon its surface. A few days after the egg is laid it hatches into a minute caterpillar that begins eating off the hairs where they are attached to the leaf, in such a way that it soon has a free space beneath a bunch of these hairs which it has more or less matted together by means of silken thread. The little caterpillar has thus provided for itself a protecting nest that effectually conceals it from birds or other enemies. It now begins feeding upon the succulent surface of the rather thick leaf, where it has removed the hairs. After several days of such feeding it moults, still under the shelter of its hairy covering. This process of moulting and feeding continues for two or three weeks, the caterpillar occasionally making a new covering as needed for its food supply.The later nests are likely to be made by folding two or three leaves together, binding them with silken thread.The caterpillar in doing this takes advantage of the fact that the terminal leaves are vertical before they have spread out, so that it is a comparatively simple matter to make a little house by binding their edges together with silken threads. The larva feeds upon the inner walls of the house it thus constructs, and as it becomes larger the buds and blossoms are also utilized for food.When the caterpillar is full grown it thus finds itself fairly well concealed within a very substantial sort of a home. Many of them have the apparent good sense to realize that this is as safe a place as they are likely to find for shelter during the period of the chrysalis. So the caterpillar makes the nest especially secure near the centre of what might be called the ceiling and in this web it entangles its hind legs and hangs downward, preparatory to changing to the chrysalis. A few hours later the skin splits apart and is wriggled off, leaving the chrysalis hanging in place of the caterpillar. About a fortnight later the butterfly emerges and crawls at once to the outside of the nest, where it rests quietly while its wings expand and its tissues harden. Then it flies away in search of the nectar of thistles and many other flowers which it visits freely.This Painted Beauty is a wonderful example of harmonious coloring. The general tone of the upper surface of the wings is fulvous, with some distinct white markings on a blackish background at the outer angles of the front pair. There is also more or less blackish shading on the base and margin of all the wings with an indistinct row of about four dots, more or less run together, near the margin of the hind wing. The under surface of the wings is even more beautiful than the upper, and furnishes a strikingexample of flower-picturing. There is a little fulvous background near the middle of the front wings, but the rest of the surface is spotted and striped with blotches and circles of gray and brown in a most intricate design. On each front wing near the outer angle are three indistinct eye-spots in a row, and on the outer half of each hind wing there are two bull's-eye circles, one smaller than the other, which form the most conspicuous feature in the marking of the insect.When full grown the caterpillars are a little more than an inch long with a general color of velvety black, marked with fine yellow lines and more or less covered with bristly spines. There is also a distinct row of whitish spots along each side beginning a short distance back of the head.This is a widely distributed butterfly, occurring from Canada to the Southern states and beyond. In most northern regions it seems to be two-brooded, the butterflies commonly hibernating as adults; but sometimes the winter is passed in the condition of the chrysalis. Along its southern range there are three and perhaps four broods each year.The Painted Lady or the CosmopoliteVanessa carduiOur story of this beautiful butterfly ought really to begin with that of one of the most successful plants in the world. Now a plant is successful from its own point of view when it is able to multiply abundantly in many different sorts of situations and to spread easily over a large area. Theplant I have in mind is the thistle, which from time immemorial has been one of the commonest neighbors of man. It is found over the whole habitable globe, as well as in many parts which are scarcely habitable. It has many advantages in its struggle for life. The roots penetrate deeply into the soil; the thickened, spiny leaves are so protected by their juices and their spines that they are molested by very few enemies; the flower stalks are also clothed in a similar armature; and the great heads of flowers are surrounded with prickly involucres that generally prevent their being eaten by browsing animals or even by phytophagous insects. The brightly colored blossoms are abundantly provided with nectar and pollen, and they attract great numbers of bees, moths, and butterflies, in order to bring about cross-fertilization. But all of these advantages are of little significance so far as wide distribution is concerned, compared with the feathery seeds which are produced in such abundance and so generally scattered by the slightest breath of wind that the word thistle-down has come into general use to express a lightly moving object. These airy seeds have been riding on the wings of the wind all over the surface of the earth for untold millions of years. Doubtless during severe storms they may be carried thousands of miles, and it is easy to think that one of them might readily go half-way round the world before it found a resting place. Wherever such a seed alighted and found the condition of a moist soil and slight protection, it would be likely soon to spring into growth and to start anew the development of its ancient race.The thistle, however, has not been entirely unmolested during its aeons of existence. There has been developingalong with it one of the most beautiful of our butterflies which has received various scientific names and the common name of the Painted Lady, although it is also often called the Thistle Butterfly and the Cosmopolite, which latter title perhaps is to be preferred. This butterfly, however, can scarcely be considered a troublesome enemy of its host plant, for it is seldom sufficiently abundant to injure the thistle appreciably. The relation between the two is rather suggestive of that mutual toleration by which two living things develop together with advantage at least to one and without serious disadvantage to the other. The universal distribution of the food plant has led to a like distribution of the butterfly. Consequently the Thistle butterfly has long been recognized as the most cosmopolitan species of its group. (See plate,page 176.)Aside from the wide distribution of its food plant and possibly correlated with it through the diversity of climatic conditions under which the insect has developed, this butterfly is remarkable for its powers of flight. Many instances are known where it has been taken at sea long distances from land. This is due not only to the propensity of the individual for taking aërial journeys, but also to the fact that this is one of the butterflies which has the instinct to congregate in swarms and to migrate long distances when thus congregated. In 1879 such a flock started from Africa and migrated to Europe.One of the most remarkable things about this butterfly is our ignorance of what it does with itself in winter. American entomologists are agreed that the adult butterfly hibernates, but where it does so seems not to be known. Here is an excellent opportunity for some young naturalist to go scouting, hunting in board piles, underloose bark, or with a flashlight searching the interiors of hollow trees to find between November and April living specimens of this butterfly. Such a discovery would be a real service to science and should at once be made known through some scientific journal. In Europe there seems to be a belief that the insect hibernates partially at least in the condition of the chrysalis.The Life-storyWhile we may not know just where the butterflies have been throughout the winter, we do know that in southern New England they begin to be seen in fields and along roadsides about the middle of May. Many of the specimens then have a ragged appearance which is a pretty good indication that they came from the chrysalis the fall before and have been lying concealed through all the weeks since. These butterflies lay their small greenish, barrel-shaped eggs on the leaves of the thistle. The mother butterfly chooses the location rather carefully and deposits only one egg upon a leaf. The butterflies continue thus to visit flowers and to lay eggs until about the middle of June when apparently they perish.About a week after the egg has thus been laid, it hatches into a small spiny caterpillar which does not take the trouble to devour its egg shell as so many other caterpillars do. Instead it crawls around to the lower side of the leaf and gnaws off enough of the silken surface of the leaf to furnish material for making a webby covering, the leaf particles being woven together by threads from the caterpillar's mouth. In this way the little creature soon provides itself with a snug enclosure which serves it as a temporary home. It remains in this home much of thetime when not eating, going out occasionally to feed upon the green tissues of the adjacent parts of the leaf.This first home of the young caterpillar, made as it is as a flat blanket upon a flat surface, can be used only by a very small larva. Consequently, the caterpillar soon finds these quarters too cramped and it deserts them to make a new home with larger space. This second nest is commonly made on the upper surface of a leaf, the edges of which are likely to be more or less drawn together and other supports connected from other leaves or a near-by stem. The caterpillar continues to use this nest number two as a place for remaining when not feeding and for protection during the process of moulting. But even this larger nest is likely to be given up about the time the caterpillar becomes half grown, and a third nest is begun in the upper part of the plant. This is likely to be very commodious, its walls being made of leaves or stems bound together by a silken web. Within this the caterpillar completes its growth, going out and in through one or more doors when it wishes to feed. Sometimes it even remains within this nest during the process of changing to the chrysalis, hanging downward from the upper part in much the same way that the caterpillar of the Painted Beauty butterfly does. In case it leaves the nest when fully developed it generally finds a place near-by in which to pupate.About ten days after the caterpillar has changed to a chrysalis it changes again to the adult butterfly. In southern New England these butterflies appear about the middle of July and lay eggs soon afterward, these eggs hatching into butterflies that change to chrysalids and change again to butterflies late in August or early in September.This autumn brood doubtless furnishes the butterflies that will be seen upon the wing the following May, so that it is pretty certain that they must find some shelter in which to pass the intervening months.The full-grown caterpillar of the Thistle butterfly is about one and a quarter inches long and of a general yellowish color, more or less marked with blackish as well as with paler lines of color. There are many transverse rows of spines along the segments, each yellowish spine having a circle of smaller ones at the top.Notwithstanding its fondness for thistles, these caterpillars occasionally feed upon various other plants. One might readily expect them to be able to live upon other composites upon which they are found, but it seems a bit strange that they should be recorded as being "especially fond of mallows."The Mourning-cloakVanessa antiopaOne of the most scholarly students of American insects has happily called the butterflies "the frail children of the air." It seems a fitting term for creatures so ethereal that they are readily wafted on the wings of the slightest breeze and so delicate in structure that they are likely to be sadly mutilated by the lightest touch of human hand. Such creatures one would say belong to regions of perpetual summer and have no place in the blizzard-swept winters of our Northern states.Yet if one goes into the snow-clad woods during one of the midwinter thaws one is likely to see in every open glade several dark-colored butterflies flitting from tree to tree, orresting with expanded wings in the sunniest spots. These butterflies obviously have endured the coldest weather and if they are to survive until another season must continue to endure still more. This species is commonly called the Mourning-cloak butterfly—not a particularly happy name for so beautiful an insect. In England it has the more suggestive title of Camberwell Beauty, and country boys are said to call it the Yellow Edge butterfly. Its general life-story has already been told onpages 112-115.The caterpillars of the Mourning-cloak butterflies are restricted to comparatively few food plants. In regions where they are not especially abundant, they are likely to be found upon willow, poplar, or elm. In general, as many observations indicate, they are as likely to be found upon any one of these food plants as upon either of the other two; but in certain localities where they become especially abundant it seems that they are more likely to occur upon the elm. On this account they have been called the Spiny Elm caterpillars. There is considerable evidence to show that they prefer the American elm to other species of the genus, although in the case of willow and poplar there seems to be little if any preference as to the species.Miss Caroline G. Soule has seen the butterflies depositing their eggs upon the white and canoe birch, and it has been recorded as feeding in Labrador and Europe upon a species of birch. There is one record of the caterpillars having been found feeding upon the hackberry, and also of their having fed greedily upon the leaves of rose bushes, and still another of their having almost defoliated a pear tree. Linden and nettle are also included in the European lists of the food plants of this species. (See plates, pages145,176.)It is evident, however, that all of these, except the threefirst named—willow, poplar, and elm—are to be regarded as exceptional cases, and that the normal food of the species is the foliage of a plant belonging to one of these three genera.It has generally been supposed that this species is double-brooded in central and southern New England, the butterflies of the first brood appearing early in July. These are said to deposit eggs which hatch into caterpillars that mature into butterflies early in September. These butterflies live through the winter, laying eggs the following spring.It is very probable that as far north as southern New Hampshire the species is commonly single-brooded. During one season when the caterpillars were unusually abundant, a very careful watch was kept for the second brood in New Hampshire and Vermont by several competent observers. Only one colony of caterpillars was found and this was at Durham in the southern part of New Hampshire near the seacoast. Consequently, it seems safe to conclude that in northern and central New England, at least, a single brood is the rule rather than the exception. This involves the conclusion that the butterflies seen upon the wing early in autumn are the same ones that developed in July, and that these same butterflies remain alive through the winter and until, in the following May, they lay their eggs. Thus there is a period of ten months of existence in the butterfly state, an extraordinary length of time for a butterfly to live.To a large extent the butterflies disappear in August, and the question arises as to what becomes of them. Our observations lead to the conclusion that they go into summer quarters similar to those which they seek out forwinter shelter. Apparently they fly about for a few days after coming from the chrysalis and then retire to cool woods, where under the side of a log or beneath the loose bark of a dead tree they settle down and to all appearances go to sleep. The instinct to remain quiet is very strong in these butterflies. In taking the accompanying photographs, I found that even shortly after coming from the chrysalis the butterflies when disturbed would fold their wings with the antennae between them, and drawing the legs against the body would lie quietly on their sides for a long time. These same butterflies would also hang downward from a limb by the hour in the hibernating position as shown in plate oppositepage 32.In the cooler weather of early autumn, the butterflies come from their retreats and fly about in the sunshine. They are especially likely to be seen along the borders of woods or in open glades. At this time they love the sunshine, and will settle in a sunny place to bask in it.Going into Winter QuartersWhen the warm days no longer tempt them abroad, the Mourning-cloaks seek shelter in many sorts of situations—under loose bark, in hollow trees, under culverts and bridges, in woodpiles, in crevices of rocks, or alongside logs lying on the ground. In such retreats they remain until the sunshine of spring again calls them forth.Prof. G. H. Parker's observations indicate that these butterflies are very sensitive to changes of temperature, and he has seen the interesting action of the butterflies crawling into their hiding places, finding that this takes place each day after they had been sunning themselves. Thus he writes:"These butterflies remain during cool spring nights in places similar to those in which they hibernate in winter,viz., in openings in stone walls, in old out-houses, in openings under the bark of trees, etc. They retire to these places with considerable regularity, so that in the open woods, where dozens of individuals may have been seen flitting about, all may have disappeared a quarter of an hour later. I have watched their retreat with some care. On a clear afternoon in early April I took my stand in a woodland where many Mourning-cloak butterflies were on the wing. They continued actively flying about till approximately four o'clock, when I began to notice a diminution in their numbers. By a quarter past four not a butterfly was to be seen. During the fifteen minutes from four o'clock on I followed two to their hiding places. One alighted on the front of a fallen tree and without expanding its wings crept immediately into a large crack in the bark. The second settled on a stone fence and crept into a hole between some loose stones. The period during which this occurred was marked not so much by a diminution of light as by a rapid fall of temperature."That the habit of lethargy in cold and of resting upon the bark of trees is practically universal with this species is shown by a statement quoted by H. G. Adams in his book, "Beautiful Butterflies," published in England in 1871. The writer quoted says: "In a wood on the summit of the Drachenfels, when the wind was rather keen, I found numbers resting on the backs of fallen trees in a state of stupor. They made no attempts to escape and when thrown into the air their wings barely opened or flapping feebly eased their fall or enabled them to seek repose on the stem of a rotten trunk."Its Rarity in EnglandIn many books this species is spoken of by its English name Camberwell Beauty. It is so called because it was first observed in the neighborhood of Camberwell in the county of Surrey, England. It seems that in that country it is a very rare species. This is a bit curious considering the fact that in America it is so extremely abundant. In his attractive little book quoted above, Mr. Adams begins the discussion of this species with this statement: "This is the crowning glory of the British butterfly collector's cabinet, and a happy man is he who gets a perfect specimen of an insect which is at once so rare and so beautiful." And later in the same discussion is this further statement concerning the scarcity of the species: "In neither the larva nor the pupa state has the insect been found, we believe, in this country where its appearance occurs, except just here and there a single specimen or two, at long and uncertain intervals. About eighty years ago it was seen in many parts of the kingdom and again in 1819, but not since then although almost every year one or more specimens are taken or seen."A curious fact in regard to the Mourning-cloak, as found in England, is that the border around the wings seems to be much more generally white than it is with us. J. O. Westwood in his book on British butterflies describes the margin as of a white or whitish color and other writers speak of the same fact. Kirby in his "Butterflies and Moths" makes this comparative statement: "The border is whitest in British specimens, and perhaps yellowest in American ones." He speaks of it also as one of the rarest British species. It is sometimes called by the common name the White Border and also occasionally the Grand Surprise, appellations which bear out what has been said above both in regard to the color of the border and the rarity of the insect.THREE MORE ANGLE-WINGSUpper surfaces at left; under surfaces at right, slightly reducedThe Buckeye (seepage 188)The Painted Beauty (seepage 163)The Cosmopolitan (seepage 166)From a drawing by W. I. BeecroftSee pages112,171THE MOURNING-CLOAKCaterpillar, chrysalis, and butterflyThe Mourning-cloaks subsist upon a considerable variety of liquid food which they suck through their long tongues. In spring, when they first come from their winter quarters, they visit the stumps of recently cut trees and suck the exuding sap, a habit which they continue whenever opportunity offers. Mr. W. F. Fiske has noticed that they commonly sip the sap of maple twigs where the squirrels have gnawed the bark. A little later they visit the willow catkins to suck the nectar secreted by these blossoms, and still later they hover about the delicate blossoms of the mayflower, or trailing arbutus, for a similar purpose. Probably many other flowers are thus rifled of their sweets, although this butterfly seems to be a less regular visitor to flowers than are many of its allies. A little later, when the aphids, or plant-lice, have become sufficiently abundant so that the so-called "honey dew" is to be found upon the infested shrubs, these Mourning-cloaks sometimes sip the liquid sweet from the surface of the leaves. In April and May they occasionally visit the flowers of moosewood, and later in the season have been observed upon the blossoms of the common milkweed. From the time the early apples ripen these butterflies may often be seen beneath the orchard trees, sipping the liquids of the fallen and decaying fruit.The Parasites of the EggsOne fine spring morning I came upon a Mourning-cloak depositing a cluster of eggs upon a willow twig. She wasso busily engaged that I was able to draw near and watch the operation for some time before she flew away. As soon as she was gone I was much interested to see a tiny parasitic fly running eagerly over the newly laid eggs, and this fly also was so busily interested in her work that I was able to cut the twig off and sit down to observe at leisure through a lens the actions of the insect. I dictated to a companion my notes of these observations and so was able to get rather a complete record of the process of oviposition.The tiny fly would stop over one of the butterfly eggs, holding its body vertical with the hind legs far back and the other legs so straightened out as to hold the front of the body high up. Then it would insert its tiny ovipositor through the egg shell and proceed to deposit an egg of its own inside of the larger egg of the butterfly. At least it seemed a safe assumption that this was what happened although of course it was impossible to see the smaller egg at the time. While thus engaged the antennae of the tiny fly were bent directly downward to the egg beneath. In about a minute the fly withdrew its ovipositor and after running around for a few seconds again settled upon another egg and repeated the operation. Then it tried again on a third egg, after which I got out my watch and began timing the process. These are the results in the case of the next dozen eggs that were laid. It required:94sec.tolayeggNo.4.Thenflymovedaround26sec.120"""""5.""""27"83"""""6.""""20"92"""""7.""""22"75"""""8.""""40"90"""""9.""""42"102"""""10.""""15"120"""""11.""""21"120"""""12.""""18"60"""""13.""""25"120"""""14.""""25"60"""""15.""""50"It thus required an average of about two minutes per egg for the laying of these fifteen eggs. I then caught the little fly and sent her to Dr. L. O. Howard, our greatest authority on this group of insects, to learn the name of the parasite. He identified it asTelenomus graptae, a well-known parasite of the eggs of the Mourning-cloak and related butterflies.The most interesting thing about this observation was the fact that the little fly had apparently begun its operation before the mother butterfly had finished laying her cluster of eggs. There were thousands of willow twigs in the immediate vicinity. How did this tiny creature arrive at this particular place at the particular moment when from its own point of view it was most needed? Had it been riding around upon the body of the butterfly waiting for the time when she should lay the eggs? Or was it attracted to them from somewhere in the immediate vicinity? That this early arrival probably takes place generally is indicated by the fact that a similar observation had been made in the White Mountains by Prof. C. W. Woodworth.The history of the egg parasite after the laying of the egg seems to be comparatively simple. It soon hatches into a tiny larva that develops within the shell at the expenseof the contents. It finally changes to a pupa which in turn changes to the little fly that gnaws a hole through the egg shell and emerges to the outer world.The Parasites of the CaterpillarsAfter hatching from the egg, the Mourning-cloak caterpillars are also subject to the attacks of various parasites. One of these is quite minute, not a great deal larger than the egg parasite. It is a tiny four-winged fly which deposits many eggs in a single caterpillar. The eggs hatch into tiny maggots that grow at the expense of the caterpillar, finally killing it and changing to four-winged flies again. As many as 145 of these parasites have been known to emerge from a single dead caterpillar. These little flies are called Chalcids by entomologists.There is still another group of four-winged flies, some of which attack the Antiopa caterpillars. These are much larger than the Chalcid flies and are called Ichneumon flies. In the case of these, only one or two parasites develop in each caterpillar or chrysalis.In addition to these various four-winged flies, there are certain two-winged flies, called Tachinid flies, that develop at the expense of the caterpillars. In New Hampshire, during recent years, these appear to have been the most abundant parasites of these insects. An egg is laid on the skin of the caterpillar by a two-winged fly, similar in general appearance to the figure below. The contents of this egg shortly develop into a tiny grub that burrows through the egg shell and the skin of the caterpillar into the inside of the body. Here it remains, absorbing the body substance of its host and gradually increasing in size. In a few weeks it becomes fully developed in thisgrub state. By this time the caterpillar has become sluggish from the effects of the parasite. If the branch upon which it feeds is disturbed, the other caterpillars are likely to crawl away, but the enfeebled victim remains in its place.Tachinid Parasite.(Slightly magnified.)Shortly after becoming full grown, the Tachinid grub breaks through the skin of the dying caterpillar and, falling to the ground, changes to a peculiar pupa; the outer skin of the grub turns brown and becomes hard, forming a protective covering for the body inside. A week or two later the insect undergoes another change and emerges as a two-winged Tachinid fly, like the one that laid the egg some weeks before.Other EnemiesBesides those insects that develop on the inside of the bodies of these Antiopa caterpillars there are other insect enemies which attack them from the outside and devour them bodily. The most notable of these, perhaps, is a large beetle commonly called the Caterpillar Hunter; it is known to entomologists asCalosoma scrutator. This is a very active insect, with large strong jaws, that runs rapidly about in search of victims. In some cases it has been observed while destroying many of the Antiopa larvae.In the Southern states a common reddish wasp—a species of Polistes—has also been observed attacking these caterpillars, and there are probably various other insects that destroy them, although definite observations showing this have not been recorded.The Antiopa caterpillars are such spiny creatures that comparatively few birds attack them. They are devoured, however, by the two species of cuckoos—the yellow-billed and black-billed—and it is probable that they are sometimes killed by Baltimore orioles and various other birds. They are also greedily devoured by toads, but of course they do not often come within the reach of these useful animals.Even the adult butterflies of this species have to be on the lookout for enemies. During the long months of their life many of them probably succumb to the attacks of birds or other creatures. I have seen but one such tragedy. While riding along a country highway with a bird-loving friend one spring day we saw a male Maryland yellow-throat flit by with a Mourning-cloak in his mouth. The bird lit on a fence, from which I startled him so that he dropped the butterfly, a worn and faded, half-dead specimen. The places where the bird held the insect were indicated by missing pieces of the wings.The American Tortoise-shellAglais milbertiThis beautiful butterfly is one of the most distinctive of all our species. It is of moderate size, its wings rarely expanding more than two inches, and it has sufficiently irregular outlines to indicate its relationship with the Angle-wings. The most striking feature of the upper surface is the broad band of orange-brown extending clear across both wings a little inside the border. The remaining surface is a darker brown marked with two orange-brownspots near the front margin of each front wing and having scattered iridescent scales which show plainly under a lens. The suggestion of the coloring of a tortoise-shell is easily seen in these rich brown tones. The under surface is a wonderful illustration of protective coloring. With wings closed and resting against the bark of trees or lying beneath the trees among fallen leaves, it would require a keen eye to detect the insect. (See plates,pages 160-161.)The American Tortoise-shell is distinctly a northern species. North of latitude forty-three degrees it seems to occur practically from ocean to ocean, extending far up toward the arctic region. It is commonly found in British America as far north as Fort Simpson in latitude sixty-one degrees. There are specimens in the British Museum collected by the explorer Ross in arctic America, and there are many in our own National Museum collected in the Hudson Bay region by various American explorers. In New England the species is abundant at times in New Hampshire, Vermont, and Maine. In the vicinity of New York City and Buffalo, New York, it is rather rare. And south of this latitude it is found chiefly at the higher elevations in mountainous districts. As a rule it is likely to vary in numbers from year to year, sometimes being extremely abundant while more commonly it is rather rare. These are the same sorts of fluctuations that we find in the case of the Mourning-cloak, the American tent caterpillar, and various other insects whose larvae live in colonies. The variation is probably due to the fact that when the caterpillars become unusually abundant they become correspondingly conspicuous and so provide a shining mark that is soon discovered by their insect enemies or by various fungous diseases.The Story of Its LifeIn its manner of laying eggs this butterfly differs from most others. The great majority of our familiar species lay their eggs one in a place or possibly two or three near together. Some species deposit several in a group, while some, like the Mourning-cloak, may lay two or three dozen in a cluster. Very few, however, deposit hundreds in a bunch. Two of these are the Baltimore and this American Tortoise-shell. In the case of the latter the eggs are loosely laid, hundreds together, upon the leaves of the common stinging nettle. Probably each female can deposit six or eight hundred eggs. In less than a week the eggs hatch into minute blackish caterpillars that feed upon the tender tissues of the leaf upon which they were born and then migrate together toward the top of the plant. In their habits they are quite similar to the caterpillars of the Mourning-cloak. As each walks it spins from its mouth a silken thread and the combined effect of hundreds of these threads is to make a noticeable silken web over the leaves. The caterpillars remain in colonies, feeding together from day to day and gradually denuding the upper branches of the nettle plant, leaving an unsightly silken web as a memento of their presence. This webbing is very suggestive of the similar result left behind by a colony of Mourning-cloak caterpillars upon the twigs of elm or poplar.When about half grown these caterpillars are likely to scatter more or less in accidental groups which may make small shelter tents from the larger leaves. In each little nest there may be four or five or more of the dark-colored caterpillars. From these shelter tents they sally forth tofeed upon the adjacent leaves and a little later become full grown as caterpillars. Each now wanders away and finding such shelter as it is able to, spins a button of silk and becomes a chrysalis. It remains in this condition but a short time before it emerges again as the beautiful butterfly.This species is commonly reputed to have three broods a year, hibernating both as a butterfly and as a chrysalis. It has been suggested, however, by Mr. W. F. Fiske, one of our most painstaking entomologists who has studied the butterflies of New Hampshire for many years, that it is more probably double-brooded with a period of aestivation during the later weeks of summer. This seems a very probable condition and it is to be hoped that some observer will make such a careful study of this species as to settle the point definitely.In the case of many butterflies the distribution of the species coincides with the distribution of the food plant. This American Tortoise-shell, however, is perhaps the exception that may prove the rule, for its southward limit is far north of the southern range of the stinging nettle. Evidently, it is a species which has developed in adjustment to the cool climate of northern regions or high altitude, and it does not easily adapt itself to a warmer territory.The White-J Butterfly or Compton TortoiseEugonia J-albumDuring bright days in March and April one is likely to find two kinds of butterflies on the wing in open glades ofthe woods. One is the familiar Mourning-cloak and the other is the Compton Tortoise—the latter generally much less abundant than the former. Both make the most of the brief periods of sunshine and quickly disappear when the sky is overcast.The Compton Tortoise butterflies which are thus abroad in early spring have been in hibernation since October. They are helping to carry the species over from one season to another, and as the days become longer and warmer they appear on the wing more and more, seeking such liquid food as the field and forest yields during the days of early spring. The sap exuding from holes in bark made by woodpeckers, or from the tappings of the maple trees by man, the nectar of willow catkins, the moisture of roadside pools—these help to yield a precarious sustenance to these butterflies after their long winter fast. They remain upon the wing week after week, while spring slowly progresses in the northern regions they inhabit. When at last the leaves push out on their food trees—willow, birch, and elm—the females lay their eggs and then, having lived to what for a butterfly is a ripe old age, they die, after nearly ten months of adult existence.Apparently the eggs are laid in clusters on the twigs, although this seems to be one of the many facts about butterflies awaiting observation by some careful student. The caterpillars feed together in small colonies but make no nest. They become full grown in about a month. They are then nearly two inches long with spinous, greenish bodies, striped with lighter lines. Some change to chrysalids about the middle of June and ten days later change again to butterflies, the first of which appear early in July while others continue to emerge for nearly a month.These butterflies may be seen rather frequently from midsummer on, visiting various flowers and sipping the juices from decaying fruits beneath the trees. At times they seem to disappear in August to reappear in October, a fact which has led some observers to suggest that there is a second brood. The caterpillars of this brood, however, have never been observed and a much more probable explanation has been made by Mr. W. F. Fiske who studied the butterflies of New Hampshire carefully for many years. He found that in the hot summer weather this butterfly goes into a seclusion similar to that of its winter rest—that is, it aestivates in summer and hibernates in winter. "The possibility that the October J-album did not represent a second brood," writes Mr. Fiske, "was rendered almost a certainty by repeated observations which failed to disclose a single specimen approximating in freshness to average August individuals, and the question of their whereabouts during the interim was unexpectedly answered one warm August day by my finding several snugly packed away under the shingles on an old roof. The theory of the aestivation of the butterflies of this group will explain a good many points hitherto obscure in the life histories of the other species."In October these butterflies seek their winter quarters, finding them in woods and groves. Apparently they commonly rest upon the bark of the trunk as well as crawl into such crevices beneath loose bark as they can find. Here they remain through fall, winter, and spring, except when called into brief periods of activity by the unwonted warmth of the winter sunshine. Then in spring they come forth again to lay the eggs for the caterpillars of the new generation.The fresh butterflies are creatures of exquisitely modulated coloring. The name Compton Tortoise has reference to the rich brown tones of the upper wing surface, suggestive of those of fine tortoise-shell. In fresh specimens much of the surface, especially in the middle and along the front border, is overlaid with iridescent purple scales. Near the front outer angle of each of the four wings there is a distinct white spot, divided near the middle by a darker line of the vein running through it. The under surface is one of the best examples of mimicry of gray bark to be found in any butterfly. The tones vary considerably in different individuals, but in all the protection must be well nigh perfect when the insect is at rest with closed wings upon the bark of a tree. The striking angularity of the wing's border doubtless helps to conceal it, and the habit of dropping motionless to the ground when disturbed must also have protective value. Near the middle of each hind wing there is a small white J which led to the specific nameJ-album.This butterfly is essentially a member of the Canadian fauna. It ranges from far north in Labrador, British America, and Alaska, south as far as Pennsylvania, but toward its southern limit it occurs only on the higher elevations of mountains like the Alleghanies.
The Painted BeautyVanessa huntera
One of the most interesting phases of the study of butterflies is to learn how often they take advantage in their life-history of any peculiarity of the food plant which hasa protective value. The Painted Beauty is an excellent illustration of this. The caterpillar feeds upon the leaves of the common Everlasting or Gnaphalium. This is an abundant and widely distributed plant, found along roadsides and in fields and pastures. It is notable for the woolly covering on stems, leaves, and flowers—this dry, hairy surface being so evident that the flowers will apparently continue in blossom when they have dried, hence its common name Everlasting or, as the French call a similar flower, Immortelle. (See plate,page 161.)
The utilization of the hairs upon the leaves is begun by the mother butterfly when she lays her egg upon the upper surface, pushing it down among the hairs so that it is almost concealed. Should you be fortunate enough to find one of these eggs you would see that it is a small, yellowish green object, looking like a tiny barrel with several vertical ribs upon its surface. A few days after the egg is laid it hatches into a minute caterpillar that begins eating off the hairs where they are attached to the leaf, in such a way that it soon has a free space beneath a bunch of these hairs which it has more or less matted together by means of silken thread. The little caterpillar has thus provided for itself a protecting nest that effectually conceals it from birds or other enemies. It now begins feeding upon the succulent surface of the rather thick leaf, where it has removed the hairs. After several days of such feeding it moults, still under the shelter of its hairy covering. This process of moulting and feeding continues for two or three weeks, the caterpillar occasionally making a new covering as needed for its food supply.
The later nests are likely to be made by folding two or three leaves together, binding them with silken thread.The caterpillar in doing this takes advantage of the fact that the terminal leaves are vertical before they have spread out, so that it is a comparatively simple matter to make a little house by binding their edges together with silken threads. The larva feeds upon the inner walls of the house it thus constructs, and as it becomes larger the buds and blossoms are also utilized for food.
When the caterpillar is full grown it thus finds itself fairly well concealed within a very substantial sort of a home. Many of them have the apparent good sense to realize that this is as safe a place as they are likely to find for shelter during the period of the chrysalis. So the caterpillar makes the nest especially secure near the centre of what might be called the ceiling and in this web it entangles its hind legs and hangs downward, preparatory to changing to the chrysalis. A few hours later the skin splits apart and is wriggled off, leaving the chrysalis hanging in place of the caterpillar. About a fortnight later the butterfly emerges and crawls at once to the outside of the nest, where it rests quietly while its wings expand and its tissues harden. Then it flies away in search of the nectar of thistles and many other flowers which it visits freely.
This Painted Beauty is a wonderful example of harmonious coloring. The general tone of the upper surface of the wings is fulvous, with some distinct white markings on a blackish background at the outer angles of the front pair. There is also more or less blackish shading on the base and margin of all the wings with an indistinct row of about four dots, more or less run together, near the margin of the hind wing. The under surface of the wings is even more beautiful than the upper, and furnishes a strikingexample of flower-picturing. There is a little fulvous background near the middle of the front wings, but the rest of the surface is spotted and striped with blotches and circles of gray and brown in a most intricate design. On each front wing near the outer angle are three indistinct eye-spots in a row, and on the outer half of each hind wing there are two bull's-eye circles, one smaller than the other, which form the most conspicuous feature in the marking of the insect.
When full grown the caterpillars are a little more than an inch long with a general color of velvety black, marked with fine yellow lines and more or less covered with bristly spines. There is also a distinct row of whitish spots along each side beginning a short distance back of the head.
This is a widely distributed butterfly, occurring from Canada to the Southern states and beyond. In most northern regions it seems to be two-brooded, the butterflies commonly hibernating as adults; but sometimes the winter is passed in the condition of the chrysalis. Along its southern range there are three and perhaps four broods each year.
The Painted Lady or the CosmopoliteVanessa cardui
Our story of this beautiful butterfly ought really to begin with that of one of the most successful plants in the world. Now a plant is successful from its own point of view when it is able to multiply abundantly in many different sorts of situations and to spread easily over a large area. Theplant I have in mind is the thistle, which from time immemorial has been one of the commonest neighbors of man. It is found over the whole habitable globe, as well as in many parts which are scarcely habitable. It has many advantages in its struggle for life. The roots penetrate deeply into the soil; the thickened, spiny leaves are so protected by their juices and their spines that they are molested by very few enemies; the flower stalks are also clothed in a similar armature; and the great heads of flowers are surrounded with prickly involucres that generally prevent their being eaten by browsing animals or even by phytophagous insects. The brightly colored blossoms are abundantly provided with nectar and pollen, and they attract great numbers of bees, moths, and butterflies, in order to bring about cross-fertilization. But all of these advantages are of little significance so far as wide distribution is concerned, compared with the feathery seeds which are produced in such abundance and so generally scattered by the slightest breath of wind that the word thistle-down has come into general use to express a lightly moving object. These airy seeds have been riding on the wings of the wind all over the surface of the earth for untold millions of years. Doubtless during severe storms they may be carried thousands of miles, and it is easy to think that one of them might readily go half-way round the world before it found a resting place. Wherever such a seed alighted and found the condition of a moist soil and slight protection, it would be likely soon to spring into growth and to start anew the development of its ancient race.
The thistle, however, has not been entirely unmolested during its aeons of existence. There has been developingalong with it one of the most beautiful of our butterflies which has received various scientific names and the common name of the Painted Lady, although it is also often called the Thistle Butterfly and the Cosmopolite, which latter title perhaps is to be preferred. This butterfly, however, can scarcely be considered a troublesome enemy of its host plant, for it is seldom sufficiently abundant to injure the thistle appreciably. The relation between the two is rather suggestive of that mutual toleration by which two living things develop together with advantage at least to one and without serious disadvantage to the other. The universal distribution of the food plant has led to a like distribution of the butterfly. Consequently the Thistle butterfly has long been recognized as the most cosmopolitan species of its group. (See plate,page 176.)
Aside from the wide distribution of its food plant and possibly correlated with it through the diversity of climatic conditions under which the insect has developed, this butterfly is remarkable for its powers of flight. Many instances are known where it has been taken at sea long distances from land. This is due not only to the propensity of the individual for taking aërial journeys, but also to the fact that this is one of the butterflies which has the instinct to congregate in swarms and to migrate long distances when thus congregated. In 1879 such a flock started from Africa and migrated to Europe.
One of the most remarkable things about this butterfly is our ignorance of what it does with itself in winter. American entomologists are agreed that the adult butterfly hibernates, but where it does so seems not to be known. Here is an excellent opportunity for some young naturalist to go scouting, hunting in board piles, underloose bark, or with a flashlight searching the interiors of hollow trees to find between November and April living specimens of this butterfly. Such a discovery would be a real service to science and should at once be made known through some scientific journal. In Europe there seems to be a belief that the insect hibernates partially at least in the condition of the chrysalis.
The Life-story
While we may not know just where the butterflies have been throughout the winter, we do know that in southern New England they begin to be seen in fields and along roadsides about the middle of May. Many of the specimens then have a ragged appearance which is a pretty good indication that they came from the chrysalis the fall before and have been lying concealed through all the weeks since. These butterflies lay their small greenish, barrel-shaped eggs on the leaves of the thistle. The mother butterfly chooses the location rather carefully and deposits only one egg upon a leaf. The butterflies continue thus to visit flowers and to lay eggs until about the middle of June when apparently they perish.
About a week after the egg has thus been laid, it hatches into a small spiny caterpillar which does not take the trouble to devour its egg shell as so many other caterpillars do. Instead it crawls around to the lower side of the leaf and gnaws off enough of the silken surface of the leaf to furnish material for making a webby covering, the leaf particles being woven together by threads from the caterpillar's mouth. In this way the little creature soon provides itself with a snug enclosure which serves it as a temporary home. It remains in this home much of thetime when not eating, going out occasionally to feed upon the green tissues of the adjacent parts of the leaf.
This first home of the young caterpillar, made as it is as a flat blanket upon a flat surface, can be used only by a very small larva. Consequently, the caterpillar soon finds these quarters too cramped and it deserts them to make a new home with larger space. This second nest is commonly made on the upper surface of a leaf, the edges of which are likely to be more or less drawn together and other supports connected from other leaves or a near-by stem. The caterpillar continues to use this nest number two as a place for remaining when not feeding and for protection during the process of moulting. But even this larger nest is likely to be given up about the time the caterpillar becomes half grown, and a third nest is begun in the upper part of the plant. This is likely to be very commodious, its walls being made of leaves or stems bound together by a silken web. Within this the caterpillar completes its growth, going out and in through one or more doors when it wishes to feed. Sometimes it even remains within this nest during the process of changing to the chrysalis, hanging downward from the upper part in much the same way that the caterpillar of the Painted Beauty butterfly does. In case it leaves the nest when fully developed it generally finds a place near-by in which to pupate.
About ten days after the caterpillar has changed to a chrysalis it changes again to the adult butterfly. In southern New England these butterflies appear about the middle of July and lay eggs soon afterward, these eggs hatching into butterflies that change to chrysalids and change again to butterflies late in August or early in September.This autumn brood doubtless furnishes the butterflies that will be seen upon the wing the following May, so that it is pretty certain that they must find some shelter in which to pass the intervening months.
The full-grown caterpillar of the Thistle butterfly is about one and a quarter inches long and of a general yellowish color, more or less marked with blackish as well as with paler lines of color. There are many transverse rows of spines along the segments, each yellowish spine having a circle of smaller ones at the top.
Notwithstanding its fondness for thistles, these caterpillars occasionally feed upon various other plants. One might readily expect them to be able to live upon other composites upon which they are found, but it seems a bit strange that they should be recorded as being "especially fond of mallows."
The Mourning-cloakVanessa antiopa
One of the most scholarly students of American insects has happily called the butterflies "the frail children of the air." It seems a fitting term for creatures so ethereal that they are readily wafted on the wings of the slightest breeze and so delicate in structure that they are likely to be sadly mutilated by the lightest touch of human hand. Such creatures one would say belong to regions of perpetual summer and have no place in the blizzard-swept winters of our Northern states.
Yet if one goes into the snow-clad woods during one of the midwinter thaws one is likely to see in every open glade several dark-colored butterflies flitting from tree to tree, orresting with expanded wings in the sunniest spots. These butterflies obviously have endured the coldest weather and if they are to survive until another season must continue to endure still more. This species is commonly called the Mourning-cloak butterfly—not a particularly happy name for so beautiful an insect. In England it has the more suggestive title of Camberwell Beauty, and country boys are said to call it the Yellow Edge butterfly. Its general life-story has already been told onpages 112-115.
The caterpillars of the Mourning-cloak butterflies are restricted to comparatively few food plants. In regions where they are not especially abundant, they are likely to be found upon willow, poplar, or elm. In general, as many observations indicate, they are as likely to be found upon any one of these food plants as upon either of the other two; but in certain localities where they become especially abundant it seems that they are more likely to occur upon the elm. On this account they have been called the Spiny Elm caterpillars. There is considerable evidence to show that they prefer the American elm to other species of the genus, although in the case of willow and poplar there seems to be little if any preference as to the species.
Miss Caroline G. Soule has seen the butterflies depositing their eggs upon the white and canoe birch, and it has been recorded as feeding in Labrador and Europe upon a species of birch. There is one record of the caterpillars having been found feeding upon the hackberry, and also of their having fed greedily upon the leaves of rose bushes, and still another of their having almost defoliated a pear tree. Linden and nettle are also included in the European lists of the food plants of this species. (See plates, pages145,176.)
It is evident, however, that all of these, except the threefirst named—willow, poplar, and elm—are to be regarded as exceptional cases, and that the normal food of the species is the foliage of a plant belonging to one of these three genera.
It has generally been supposed that this species is double-brooded in central and southern New England, the butterflies of the first brood appearing early in July. These are said to deposit eggs which hatch into caterpillars that mature into butterflies early in September. These butterflies live through the winter, laying eggs the following spring.
It is very probable that as far north as southern New Hampshire the species is commonly single-brooded. During one season when the caterpillars were unusually abundant, a very careful watch was kept for the second brood in New Hampshire and Vermont by several competent observers. Only one colony of caterpillars was found and this was at Durham in the southern part of New Hampshire near the seacoast. Consequently, it seems safe to conclude that in northern and central New England, at least, a single brood is the rule rather than the exception. This involves the conclusion that the butterflies seen upon the wing early in autumn are the same ones that developed in July, and that these same butterflies remain alive through the winter and until, in the following May, they lay their eggs. Thus there is a period of ten months of existence in the butterfly state, an extraordinary length of time for a butterfly to live.
To a large extent the butterflies disappear in August, and the question arises as to what becomes of them. Our observations lead to the conclusion that they go into summer quarters similar to those which they seek out forwinter shelter. Apparently they fly about for a few days after coming from the chrysalis and then retire to cool woods, where under the side of a log or beneath the loose bark of a dead tree they settle down and to all appearances go to sleep. The instinct to remain quiet is very strong in these butterflies. In taking the accompanying photographs, I found that even shortly after coming from the chrysalis the butterflies when disturbed would fold their wings with the antennae between them, and drawing the legs against the body would lie quietly on their sides for a long time. These same butterflies would also hang downward from a limb by the hour in the hibernating position as shown in plate oppositepage 32.
In the cooler weather of early autumn, the butterflies come from their retreats and fly about in the sunshine. They are especially likely to be seen along the borders of woods or in open glades. At this time they love the sunshine, and will settle in a sunny place to bask in it.
Going into Winter Quarters
When the warm days no longer tempt them abroad, the Mourning-cloaks seek shelter in many sorts of situations—under loose bark, in hollow trees, under culverts and bridges, in woodpiles, in crevices of rocks, or alongside logs lying on the ground. In such retreats they remain until the sunshine of spring again calls them forth.
Prof. G. H. Parker's observations indicate that these butterflies are very sensitive to changes of temperature, and he has seen the interesting action of the butterflies crawling into their hiding places, finding that this takes place each day after they had been sunning themselves. Thus he writes:
"These butterflies remain during cool spring nights in places similar to those in which they hibernate in winter,viz., in openings in stone walls, in old out-houses, in openings under the bark of trees, etc. They retire to these places with considerable regularity, so that in the open woods, where dozens of individuals may have been seen flitting about, all may have disappeared a quarter of an hour later. I have watched their retreat with some care. On a clear afternoon in early April I took my stand in a woodland where many Mourning-cloak butterflies were on the wing. They continued actively flying about till approximately four o'clock, when I began to notice a diminution in their numbers. By a quarter past four not a butterfly was to be seen. During the fifteen minutes from four o'clock on I followed two to their hiding places. One alighted on the front of a fallen tree and without expanding its wings crept immediately into a large crack in the bark. The second settled on a stone fence and crept into a hole between some loose stones. The period during which this occurred was marked not so much by a diminution of light as by a rapid fall of temperature."
That the habit of lethargy in cold and of resting upon the bark of trees is practically universal with this species is shown by a statement quoted by H. G. Adams in his book, "Beautiful Butterflies," published in England in 1871. The writer quoted says: "In a wood on the summit of the Drachenfels, when the wind was rather keen, I found numbers resting on the backs of fallen trees in a state of stupor. They made no attempts to escape and when thrown into the air their wings barely opened or flapping feebly eased their fall or enabled them to seek repose on the stem of a rotten trunk."
Its Rarity in England
In many books this species is spoken of by its English name Camberwell Beauty. It is so called because it was first observed in the neighborhood of Camberwell in the county of Surrey, England. It seems that in that country it is a very rare species. This is a bit curious considering the fact that in America it is so extremely abundant. In his attractive little book quoted above, Mr. Adams begins the discussion of this species with this statement: "This is the crowning glory of the British butterfly collector's cabinet, and a happy man is he who gets a perfect specimen of an insect which is at once so rare and so beautiful." And later in the same discussion is this further statement concerning the scarcity of the species: "In neither the larva nor the pupa state has the insect been found, we believe, in this country where its appearance occurs, except just here and there a single specimen or two, at long and uncertain intervals. About eighty years ago it was seen in many parts of the kingdom and again in 1819, but not since then although almost every year one or more specimens are taken or seen."
A curious fact in regard to the Mourning-cloak, as found in England, is that the border around the wings seems to be much more generally white than it is with us. J. O. Westwood in his book on British butterflies describes the margin as of a white or whitish color and other writers speak of the same fact. Kirby in his "Butterflies and Moths" makes this comparative statement: "The border is whitest in British specimens, and perhaps yellowest in American ones." He speaks of it also as one of the rarest British species. It is sometimes called by the common name the White Border and also occasionally the Grand Surprise, appellations which bear out what has been said above both in regard to the color of the border and the rarity of the insect.
THREE MORE ANGLE-WINGSUpper surfaces at left; under surfaces at right, slightly reducedThe Buckeye (seepage 188)The Painted Beauty (seepage 163)The Cosmopolitan (seepage 166)
THREE MORE ANGLE-WINGSUpper surfaces at left; under surfaces at right, slightly reducedThe Buckeye (seepage 188)The Painted Beauty (seepage 163)The Cosmopolitan (seepage 166)
From a drawing by W. I. BeecroftSee pages112,171THE MOURNING-CLOAKCaterpillar, chrysalis, and butterfly
From a drawing by W. I. BeecroftSee pages112,171THE MOURNING-CLOAKCaterpillar, chrysalis, and butterfly
From a drawing by W. I. Beecroft
See pages112,171
The Mourning-cloaks subsist upon a considerable variety of liquid food which they suck through their long tongues. In spring, when they first come from their winter quarters, they visit the stumps of recently cut trees and suck the exuding sap, a habit which they continue whenever opportunity offers. Mr. W. F. Fiske has noticed that they commonly sip the sap of maple twigs where the squirrels have gnawed the bark. A little later they visit the willow catkins to suck the nectar secreted by these blossoms, and still later they hover about the delicate blossoms of the mayflower, or trailing arbutus, for a similar purpose. Probably many other flowers are thus rifled of their sweets, although this butterfly seems to be a less regular visitor to flowers than are many of its allies. A little later, when the aphids, or plant-lice, have become sufficiently abundant so that the so-called "honey dew" is to be found upon the infested shrubs, these Mourning-cloaks sometimes sip the liquid sweet from the surface of the leaves. In April and May they occasionally visit the flowers of moosewood, and later in the season have been observed upon the blossoms of the common milkweed. From the time the early apples ripen these butterflies may often be seen beneath the orchard trees, sipping the liquids of the fallen and decaying fruit.
The Parasites of the Eggs
One fine spring morning I came upon a Mourning-cloak depositing a cluster of eggs upon a willow twig. She wasso busily engaged that I was able to draw near and watch the operation for some time before she flew away. As soon as she was gone I was much interested to see a tiny parasitic fly running eagerly over the newly laid eggs, and this fly also was so busily interested in her work that I was able to cut the twig off and sit down to observe at leisure through a lens the actions of the insect. I dictated to a companion my notes of these observations and so was able to get rather a complete record of the process of oviposition.
The tiny fly would stop over one of the butterfly eggs, holding its body vertical with the hind legs far back and the other legs so straightened out as to hold the front of the body high up. Then it would insert its tiny ovipositor through the egg shell and proceed to deposit an egg of its own inside of the larger egg of the butterfly. At least it seemed a safe assumption that this was what happened although of course it was impossible to see the smaller egg at the time. While thus engaged the antennae of the tiny fly were bent directly downward to the egg beneath. In about a minute the fly withdrew its ovipositor and after running around for a few seconds again settled upon another egg and repeated the operation. Then it tried again on a third egg, after which I got out my watch and began timing the process. These are the results in the case of the next dozen eggs that were laid. It required:
It thus required an average of about two minutes per egg for the laying of these fifteen eggs. I then caught the little fly and sent her to Dr. L. O. Howard, our greatest authority on this group of insects, to learn the name of the parasite. He identified it asTelenomus graptae, a well-known parasite of the eggs of the Mourning-cloak and related butterflies.
The most interesting thing about this observation was the fact that the little fly had apparently begun its operation before the mother butterfly had finished laying her cluster of eggs. There were thousands of willow twigs in the immediate vicinity. How did this tiny creature arrive at this particular place at the particular moment when from its own point of view it was most needed? Had it been riding around upon the body of the butterfly waiting for the time when she should lay the eggs? Or was it attracted to them from somewhere in the immediate vicinity? That this early arrival probably takes place generally is indicated by the fact that a similar observation had been made in the White Mountains by Prof. C. W. Woodworth.
The history of the egg parasite after the laying of the egg seems to be comparatively simple. It soon hatches into a tiny larva that develops within the shell at the expenseof the contents. It finally changes to a pupa which in turn changes to the little fly that gnaws a hole through the egg shell and emerges to the outer world.
The Parasites of the Caterpillars
After hatching from the egg, the Mourning-cloak caterpillars are also subject to the attacks of various parasites. One of these is quite minute, not a great deal larger than the egg parasite. It is a tiny four-winged fly which deposits many eggs in a single caterpillar. The eggs hatch into tiny maggots that grow at the expense of the caterpillar, finally killing it and changing to four-winged flies again. As many as 145 of these parasites have been known to emerge from a single dead caterpillar. These little flies are called Chalcids by entomologists.
There is still another group of four-winged flies, some of which attack the Antiopa caterpillars. These are much larger than the Chalcid flies and are called Ichneumon flies. In the case of these, only one or two parasites develop in each caterpillar or chrysalis.
In addition to these various four-winged flies, there are certain two-winged flies, called Tachinid flies, that develop at the expense of the caterpillars. In New Hampshire, during recent years, these appear to have been the most abundant parasites of these insects. An egg is laid on the skin of the caterpillar by a two-winged fly, similar in general appearance to the figure below. The contents of this egg shortly develop into a tiny grub that burrows through the egg shell and the skin of the caterpillar into the inside of the body. Here it remains, absorbing the body substance of its host and gradually increasing in size. In a few weeks it becomes fully developed in thisgrub state. By this time the caterpillar has become sluggish from the effects of the parasite. If the branch upon which it feeds is disturbed, the other caterpillars are likely to crawl away, but the enfeebled victim remains in its place.
Tachinid Parasite.(Slightly magnified.)
Tachinid Parasite.(Slightly magnified.)
Shortly after becoming full grown, the Tachinid grub breaks through the skin of the dying caterpillar and, falling to the ground, changes to a peculiar pupa; the outer skin of the grub turns brown and becomes hard, forming a protective covering for the body inside. A week or two later the insect undergoes another change and emerges as a two-winged Tachinid fly, like the one that laid the egg some weeks before.
Other Enemies
Besides those insects that develop on the inside of the bodies of these Antiopa caterpillars there are other insect enemies which attack them from the outside and devour them bodily. The most notable of these, perhaps, is a large beetle commonly called the Caterpillar Hunter; it is known to entomologists asCalosoma scrutator. This is a very active insect, with large strong jaws, that runs rapidly about in search of victims. In some cases it has been observed while destroying many of the Antiopa larvae.
In the Southern states a common reddish wasp—a species of Polistes—has also been observed attacking these caterpillars, and there are probably various other insects that destroy them, although definite observations showing this have not been recorded.
The Antiopa caterpillars are such spiny creatures that comparatively few birds attack them. They are devoured, however, by the two species of cuckoos—the yellow-billed and black-billed—and it is probable that they are sometimes killed by Baltimore orioles and various other birds. They are also greedily devoured by toads, but of course they do not often come within the reach of these useful animals.
Even the adult butterflies of this species have to be on the lookout for enemies. During the long months of their life many of them probably succumb to the attacks of birds or other creatures. I have seen but one such tragedy. While riding along a country highway with a bird-loving friend one spring day we saw a male Maryland yellow-throat flit by with a Mourning-cloak in his mouth. The bird lit on a fence, from which I startled him so that he dropped the butterfly, a worn and faded, half-dead specimen. The places where the bird held the insect were indicated by missing pieces of the wings.
The American Tortoise-shellAglais milberti
This beautiful butterfly is one of the most distinctive of all our species. It is of moderate size, its wings rarely expanding more than two inches, and it has sufficiently irregular outlines to indicate its relationship with the Angle-wings. The most striking feature of the upper surface is the broad band of orange-brown extending clear across both wings a little inside the border. The remaining surface is a darker brown marked with two orange-brownspots near the front margin of each front wing and having scattered iridescent scales which show plainly under a lens. The suggestion of the coloring of a tortoise-shell is easily seen in these rich brown tones. The under surface is a wonderful illustration of protective coloring. With wings closed and resting against the bark of trees or lying beneath the trees among fallen leaves, it would require a keen eye to detect the insect. (See plates,pages 160-161.)
The American Tortoise-shell is distinctly a northern species. North of latitude forty-three degrees it seems to occur practically from ocean to ocean, extending far up toward the arctic region. It is commonly found in British America as far north as Fort Simpson in latitude sixty-one degrees. There are specimens in the British Museum collected by the explorer Ross in arctic America, and there are many in our own National Museum collected in the Hudson Bay region by various American explorers. In New England the species is abundant at times in New Hampshire, Vermont, and Maine. In the vicinity of New York City and Buffalo, New York, it is rather rare. And south of this latitude it is found chiefly at the higher elevations in mountainous districts. As a rule it is likely to vary in numbers from year to year, sometimes being extremely abundant while more commonly it is rather rare. These are the same sorts of fluctuations that we find in the case of the Mourning-cloak, the American tent caterpillar, and various other insects whose larvae live in colonies. The variation is probably due to the fact that when the caterpillars become unusually abundant they become correspondingly conspicuous and so provide a shining mark that is soon discovered by their insect enemies or by various fungous diseases.
The Story of Its Life
In its manner of laying eggs this butterfly differs from most others. The great majority of our familiar species lay their eggs one in a place or possibly two or three near together. Some species deposit several in a group, while some, like the Mourning-cloak, may lay two or three dozen in a cluster. Very few, however, deposit hundreds in a bunch. Two of these are the Baltimore and this American Tortoise-shell. In the case of the latter the eggs are loosely laid, hundreds together, upon the leaves of the common stinging nettle. Probably each female can deposit six or eight hundred eggs. In less than a week the eggs hatch into minute blackish caterpillars that feed upon the tender tissues of the leaf upon which they were born and then migrate together toward the top of the plant. In their habits they are quite similar to the caterpillars of the Mourning-cloak. As each walks it spins from its mouth a silken thread and the combined effect of hundreds of these threads is to make a noticeable silken web over the leaves. The caterpillars remain in colonies, feeding together from day to day and gradually denuding the upper branches of the nettle plant, leaving an unsightly silken web as a memento of their presence. This webbing is very suggestive of the similar result left behind by a colony of Mourning-cloak caterpillars upon the twigs of elm or poplar.
When about half grown these caterpillars are likely to scatter more or less in accidental groups which may make small shelter tents from the larger leaves. In each little nest there may be four or five or more of the dark-colored caterpillars. From these shelter tents they sally forth tofeed upon the adjacent leaves and a little later become full grown as caterpillars. Each now wanders away and finding such shelter as it is able to, spins a button of silk and becomes a chrysalis. It remains in this condition but a short time before it emerges again as the beautiful butterfly.
This species is commonly reputed to have three broods a year, hibernating both as a butterfly and as a chrysalis. It has been suggested, however, by Mr. W. F. Fiske, one of our most painstaking entomologists who has studied the butterflies of New Hampshire for many years, that it is more probably double-brooded with a period of aestivation during the later weeks of summer. This seems a very probable condition and it is to be hoped that some observer will make such a careful study of this species as to settle the point definitely.
In the case of many butterflies the distribution of the species coincides with the distribution of the food plant. This American Tortoise-shell, however, is perhaps the exception that may prove the rule, for its southward limit is far north of the southern range of the stinging nettle. Evidently, it is a species which has developed in adjustment to the cool climate of northern regions or high altitude, and it does not easily adapt itself to a warmer territory.
The White-J Butterfly or Compton TortoiseEugonia J-album
During bright days in March and April one is likely to find two kinds of butterflies on the wing in open glades ofthe woods. One is the familiar Mourning-cloak and the other is the Compton Tortoise—the latter generally much less abundant than the former. Both make the most of the brief periods of sunshine and quickly disappear when the sky is overcast.
The Compton Tortoise butterflies which are thus abroad in early spring have been in hibernation since October. They are helping to carry the species over from one season to another, and as the days become longer and warmer they appear on the wing more and more, seeking such liquid food as the field and forest yields during the days of early spring. The sap exuding from holes in bark made by woodpeckers, or from the tappings of the maple trees by man, the nectar of willow catkins, the moisture of roadside pools—these help to yield a precarious sustenance to these butterflies after their long winter fast. They remain upon the wing week after week, while spring slowly progresses in the northern regions they inhabit. When at last the leaves push out on their food trees—willow, birch, and elm—the females lay their eggs and then, having lived to what for a butterfly is a ripe old age, they die, after nearly ten months of adult existence.
Apparently the eggs are laid in clusters on the twigs, although this seems to be one of the many facts about butterflies awaiting observation by some careful student. The caterpillars feed together in small colonies but make no nest. They become full grown in about a month. They are then nearly two inches long with spinous, greenish bodies, striped with lighter lines. Some change to chrysalids about the middle of June and ten days later change again to butterflies, the first of which appear early in July while others continue to emerge for nearly a month.
These butterflies may be seen rather frequently from midsummer on, visiting various flowers and sipping the juices from decaying fruits beneath the trees. At times they seem to disappear in August to reappear in October, a fact which has led some observers to suggest that there is a second brood. The caterpillars of this brood, however, have never been observed and a much more probable explanation has been made by Mr. W. F. Fiske who studied the butterflies of New Hampshire carefully for many years. He found that in the hot summer weather this butterfly goes into a seclusion similar to that of its winter rest—that is, it aestivates in summer and hibernates in winter. "The possibility that the October J-album did not represent a second brood," writes Mr. Fiske, "was rendered almost a certainty by repeated observations which failed to disclose a single specimen approximating in freshness to average August individuals, and the question of their whereabouts during the interim was unexpectedly answered one warm August day by my finding several snugly packed away under the shingles on an old roof. The theory of the aestivation of the butterflies of this group will explain a good many points hitherto obscure in the life histories of the other species."
In October these butterflies seek their winter quarters, finding them in woods and groves. Apparently they commonly rest upon the bark of the trunk as well as crawl into such crevices beneath loose bark as they can find. Here they remain through fall, winter, and spring, except when called into brief periods of activity by the unwonted warmth of the winter sunshine. Then in spring they come forth again to lay the eggs for the caterpillars of the new generation.
The fresh butterflies are creatures of exquisitely modulated coloring. The name Compton Tortoise has reference to the rich brown tones of the upper wing surface, suggestive of those of fine tortoise-shell. In fresh specimens much of the surface, especially in the middle and along the front border, is overlaid with iridescent purple scales. Near the front outer angle of each of the four wings there is a distinct white spot, divided near the middle by a darker line of the vein running through it. The under surface is one of the best examples of mimicry of gray bark to be found in any butterfly. The tones vary considerably in different individuals, but in all the protection must be well nigh perfect when the insect is at rest with closed wings upon the bark of a tree. The striking angularity of the wing's border doubtless helps to conceal it, and the habit of dropping motionless to the ground when disturbed must also have protective value. Near the middle of each hind wing there is a small white J which led to the specific nameJ-album.
This butterfly is essentially a member of the Canadian fauna. It ranges from far north in Labrador, British America, and Alaska, south as far as Pennsylvania, but toward its southern limit it occurs only on the higher elevations of mountains like the Alleghanies.