By DR. W. J. HOLLAND

THE MENTOR · DEPARTMENT OF NATURAL HISTORY

AUGUST 2, 1915

The earliest memories of my childhood cluster about a little manse in the countryside. In winter, when the drifts were deep and the house was snowbound, a usual recreation was to look at the cabinets containing shells collected in Jamaica by my father during his residence as a missionary on that island. I preferred, however, to feast my eyes on the contents of certain flat boxes of Jamaica cedar, in which many of the gorgeous moths and butterflies, as well as other insects, of that sunny island were displayed.

When spring and summer came I was very busy gathering plants, pressing them for my little herbarium, and collecting shells which I found in the woodlands and when wading the streams. Among insects the beetles and butterflies pleased me most. Later my home was in North Carolina, whither the family removed from central Ohio when I was a child of ten. Here the same process went on, with the added pleasure of being near a library, in which, among other books, was a copy of Wilson and Bonaparte’s “American Ornithology,” many of the plates in which I copied, and Say’s work on “American Entomology.” The collection of plants and insects grew apace, and I was allowed to begin to stuff and mount birds.

In 1863 I came north, and for ten years my life was passed in college and professional schools, where I had little time to study ornithology and entomology. But the love of living things survived, and when, at last settled in active professional life, I began to feel the need of some pursuit which would furnish a physical as well as intellectual recreation, I reverted to the study of insects. This took me into the woods and fields.

Having begun to collect insects, I made up my mind that I must learn to know all about them. I sought for books on the subject. There were none of any value in the libraries about me. I then began to buy books, and have continued, until today I possess a collection of works upon entomology which is said to be the largest in private hands in America. I began to seek information from other students of the subject. The circle of my correspondence has grown until it covers many lands. One of my correspondents, the late W. H. Edwards of Coalburg, West Virginia, wrote to me that he wished to publish the third volume of his magnificent work, “The Butterflies of North America,” and therefore contemplated offering his collection to the British Museum in order to obtain the necessary funds. I replied to him that I would undertake to defray the expense of bringing out the third volume of his work, provided he would turn over the collection to me, so that it might be incorporated with my own. He accepted my offer, and I thus saved for America its most important collection of butterflies. I bought many other collections from time to time. I traveled widely, always collecting, and I employed men to collect for me in foreign lands. Today my collection is one of the largest in existence, containing tens of thousands of species and hundreds of thousands of specimens.

THE BUTTERFLY BOOK

To learn what I have involved a large outlay of money and much patient study. When, therefore, it was suggested to me to prepare a comprehensive book on the butterflies of the United States and Canada I resolved to undertake the task; if for no other reason, to spare the rising generation of young Americans from the expense and trouble to which I had been subjected in trying to master the subject. I resolved to illustrate the book profusely, using so far as possible the types or identical specimens on which Edwards and others had founded their descriptions. The result was “The Butterfly Book,” and I am now following that up with a small manual entitled “The Butterfly Guide.” Both of these works are illustrated with colored figures. With these books the boys and girls of America are no longer compelled to wade, as I did, through piles of books and pamphlets in order to get the information they desire.

THE VALUE OF THE STUDY OF BUTTERFLIES

I feel that a brief recital of the way in which I came to be a student of this delightful subject may interest others, and the story may encourage some of the bright boys of America to take up the study of entomology earnestly. It is no mean subject. There was a time when “bugologists,” as students of insect life were facetiously called, were classified as a variety of harmless cranks; but that day has passed. The discovery that some knowledge of entomology is necessary to success in agriculture, and that many diseases are due to infection brought about by insects, has led the public to recognize the value of these pursuits from a social and economic standpoint. But enough of this! Now for the butterflies!

Butterflies form one of the two suborders of the order Lepidoptera, or “scaly-winged insects.” There are many orders of insects. Lord Walsingham some years ago in an address stated that there were not less than three million species of insects in this little world of ours. Tens of thousands of species of Lepidoptera have already been named and classified. Of butterflies there are twenty thousand species and varieties known, and of moths there are about five times as many. In the United States we have about six hundred and fifty species of butterflies, and six thousand species of moths. New species are still being turned up. Adam did not give names to all living things. He left his job unfinished, and “the sons of Adam” since his day have been carrying on the good work, and most vigorously during the last hundred years. The work of naming and describing species new to science is going on valorously at the present time. The last volume of “The ZoÖlogical Record,” which has just been issued, shows that in 1913 nearly three thousand strictly scientific books and papers about insects were published, not to speak of the innumerable publications of a popular character upon the same subject which were printed during that year. The same volume shows that no less than two hundred and twenty-five new species of butterflies alone were described during the year, besides a host of so-called varieties. The new species were principally from Africa, Asia, and South America.

As I have said, butterflies are “scaly-winged insects.” Anyone who has ever taken a moth or butterfly into his fingers has observed that the creature in its struggles leaves behind a dustlike substance. Examined under a microscope, this is seen to be composed of minute scales. Magnified forms of some of these scales are represented in Figure 1; while in Figure 2 there is shown a little patch of the scales on the wing of the common Cabbage butterfly, they being arranged somewhat as the shingles upon the roof of a house, or the scales upon the sides of a fish.

ORGANIZATION OF BUTTERFLIES

Butterflies possess a remarkably perfect organization, which includes the possession of senses and a considerable measure of intelligence, when we consider the relative lowliness of their station in the scale of being. Butterflies can see. They have, as all insects have, compound eyes, made up of a number of facets, so that they can look upward, downward, forward, and backward all at the same time. Their antennÆ (or feelers, as they are sometimes erroneously called) are most probably organs for smelling. Their organs for hearing, if they have any, are located upon their legs, as they are in the grasshoppers and other insects. But butterflies do not appear to be talkative, as the grasshoppers and crickets are; though some species can make curious clicking sounds, as some moths can make squeaking sounds. That they can taste is more than likely. Connected with the proboscis of butterflies, through which they suck the honey of flowers, there are, no doubt, gustatory nerves. Their brains, if the nerve-knot in the head can be so called, are not very large; but their instincts in some respects are marvelous. What, for instance, could be more wonderful than the manner in which the female butterfly, without having received a botanical education, infallibly selects the right plant upon which to lay her eggs, so that her progeny, which she never lives to see, may obtain proper nourishment? Nobody ever saw a female Swallowtail lay her eggs upon pine or clover; nobody ever saw a Cabbage butterfly lay her eggs upon other than a cruciferous plant,—either a cabbage, or one of its cousins, as plant relationships go.

WONDERS OF TRANSFORMATION

One of the most wonderful things in the world of life is the manner in which insects and butterflies, and moths in particular, undergo transformation, passing from the egg into the caterpillar, then changing into the chrysalis, and finally emerging as the winged insect, fluttering among the flowers.

The eggs of butterflies are beautiful objects when examined under a microscope. Some are shaped like spheres, some like cones, some like spindles, others like turbans. They are fluted, ribbed, pitted, sculptured, in a multitude of ways. In color they are as various as the eggs of birds. Figure 3 shows the egg of the Viceroy (Basilarchia disippus), one of the Admirals belonging to the same group of insects as those which are figured on one of the plates of “The Butterfly Book,” reproduced with this article. Figure 4 shows the egg of the Monarch, or common “Milkweed butterfly” (Anosia plexippus), which the Viceroy mimics in the color and markings of its wings.

When the caterpillar within the egg has reached its full development the top of the egg splits off, as if a lid had been lifted, and the little creature crawls out, and generally makes its first meal upon the shell which it has just vacated, thus whetting its appetite for future banquets, treating the shell as a hors d’oeuvre. The larvÆ of most butterflies and moths feed on vegetable food; but there are some curious species, even of butterflies, which are carnivorous, the caterpillars of which devour mealy bugs and the larvÆ of ants. The ant-eating species are found in Africa, Asia, and Australia.

THE PRODUCTION OF SILK

Caterpillars have the remarkable power of producing silk. Silk is a viscous fluid secreted by long glands, which are near the back of the caterpillar, and communicate with a little, tubelike organ near the jaws, called the spinneret, through which the silk is voided, instantly becoming, on contact with the air, a tough elastic fiber. Out of the silk thus secreted the caterpillars of butterflies spin threads, which they lay along the leaves and branches to guide themselves from place to place. From the silk many species weave little shelters, or tents, in which they are protected through the cold of winter. From the same delicate material they fashion the little knobs, buttons, and girdles by which the chrysalids are supported. The larvÆ of butterflies do not spin cocoons: this is done only by the caterpillars of moths.

Caterpillars, as they develop, shed their skins a number of times. When the little caterpillar has “grown too big for its breeches” it anchors itself by a few threads to a fixed spot, the skin splits along the back, and, being securely tied in place, remains fast, while the caterpillar crawls out of it. The larvÆ begins then to feed and grow again, but often treats the shed skin as it treated the shell of the egg, using it as a sort of “first course” before resuming the more substantial vegetable diet.

After the caterpillar has molted four or five times it is transformed into a chrysalis, reverting to a stationary condition, fixed as immovably as it was fixed when it was only an egg. The process of transformation is wonderful, and well repays attention. Among butterflies there are three kinds of chrysalids,—those which are pendant from a knob of silk, those which are supported by girdles as well as by a silken knob, and those which are free and lie loose between leaves and rubbish, stitched together with a few strands of silk. The chrysalids of the “brush-footed butterflies” (NymphalidÆ) are always pendant; those of the other families are cinctured, or provided with girdles, except the “skippers” (HesperiidÆ), the chrysalids of which are free, and often are found on the ground, like the chrysalids of moths.

Figure 5 shows a caterpillar of the Monarch or Milkweed butterfly undergoing the change into a chrysalis. There comes a critical moment when the creature has wriggled itself nearly out of its skin, and when the only thing to keep it hanging in its place is a fold of this skin caught, as shown at c, between two segments or rings of the abdomen. Thus suspended, it feels about with the cremaster, as the spine at the end of its tail is called, which is full of minute curved hooklets at its end. As soon as the creature feels these hooklets securely gripping into the silk of the button above, it straightens out, and lets go its hold upon the old skin and assumes the form given in Figure 6, which gives the outline of the perfect chrysalis of this species,—a truly beautiful object, pale, pearly green in color, adorned with spots of burnished gold. Figure 7 shows the cinctured chrysalis of the Pipevine Swallowtail. After sufficient time has elapsed to permit of certain developments which take place in the chrysalis, the butterfly emerges. The thing, which has slept as if in a coffin, comes forth on airy wings to disport itself among the flowers. Little wonder that poets have seen in this transformation an emblem of the Resurrection!

Some of the butterflies of the United States belong to genera which are not confined to this country, but which occur also in the Eastern Hemisphere. Indeed, some few species are identically the same as are found in Europe and Asia. The Red Admiral (Vanessa atalanta) and the Mourning Cloak (Vanessa antiopa) are as familiar to English and German schoolboys as they are to boys in America. The Painted Lady (Pyrameis cardui), known also as the Thistle butterfly, is a cosmopolitan, and occurs all over the world, except perhaps in the hot jungles of the Kongo and the Amazons. The Mourning Cloak hibernates as a butterfly. In February, 1915, one of the guards in the Carnegie Museum found a specimen of this butterfly which had flown into the building. The day had been mild, and it had ventured forth from its hiding place under the eaves, or in a hollow tree. These butterflies may be found early in spring, as soon as the sap begins to flow, congregating in the sugar camps and sipping the drip of the maple trees. Comparatively few butterflies pass the winter in the winged form, but undergo its rigors as chrysalids or as larvÆ.

MIGRATION OF BUTTERFLIES

Most of the butterflies of the United States show a relationship to those of the lands south of us. As the ice at the end of the Glacial Period retreated there was an invasion of forms from the south. The Monarch, one of our very commonest species, makes an annual migration into the northern parts of the continent, coming up from the south, as the milkweeds begin to sprout and put forth leaves, and then in autumn retreats again to “lands of sun.” The species goes far north into Canada, and in the fall of the year huge swarms of the retiring insects may be seen clustering upon trees on the northern shores of the Great Lakes, and also about Cape May in New Jersey. Many, no doubt, are drowned in the lakes and in the ocean as they try to make their way farther south.

Among the most conspicuous and beautiful butterflies of the United States are the Swallowtails, which belong to the genus Papilio. We have many species. There are only three found in all Europe. One of these (Papilio machaon), now nearly extinct in England, surviving only in the fens of Cambridge and Norfolk, has many first cousins in North America, one of which (Papilio zelicaon) is represented on the plate entitled “A Group of Swallowtails.” The metropolis of the Machaon group of Swallowtails is North America, and species belonging to it are found from Newfoundland to Central America. I have a strong suspicion that the butterflies of this group originated in the New World, as did the horse, the camel, and many other animals, and that at a time when North America and Asia were connected with each other in the region of Bering Sea, as we know they were, this insect “went west” and finally established a colony in England, which was at about that time also hitched fast to the continent of Europe.

GREAT SEX DIFFERENCES

Another group of butterflies which are nobly represented in North America are the Fritillaries, belonging to the genera Argynnis and Brenthis. A group of these insects is shown in one of the plates. The reader will observe how great a difference there is between the males and the females, especially of Argynnis Diana. When the sexes thus differ they are said to be “sexually dimorphic.” There are other kinds of dimorphism. When butterflies have several broods it has been observed that those of the spring brood differ in form and markings from those of the summer brood, and again from those which come forth in the fall of the year. Such species are said to be “seasonally dimorphic.” In the tropics we recognize what are known as “dry season forms” and “rainy season forms,” which are often very unlike each other. Sexual dimorphism is not so pronounced in all species of the genus Argynnis as it is in A. Diana. The Fritillaries have their metropolis in North America, but are also well represented in Asia, Europe, and to some degree in Africa and in South America. In the latter continent the species occur among the cool Andean regions and in the far south, in Patagonia. It is a curious fact that on the flanks of Mounts Kenia and Kilimanjaro, in Africa, separated by thousands of miles from their congeners, there are species of this group of butterflies. How did they get there? The geologist maybe can answer.

America is rich in species belonging to the family of the HesperiidÆ or “Skippers.” They are well named, as anyone who has watched them skipping and gamboling among the flowers can testify. They seem to be in some respects intermediate between the other butterflies and the moths.

An adequate account of the breeding of butterflies and of the methods of preserving them for study and display would require another article. I will then, at this time, simply refer the curious to the books already written about these things, and, if any of The Mentor readers are tempted to find the secret of eternal youth, by becoming entomologists, they will discover that every library of any size has in it today copies of the books they need to guide them. That was not the case forty years ago.

THE UTILITY OF ENTOMOLOGY

The annual loss suffered by agricultural communities through ignorance of entomological facts is very great. Every plant has its insect enemy, or, more correctly, its insect lover, which feeds upon it, delights in its luxuriance, but makes short work, it may be of leaves, it may be of flowers, it may be of fruit. It has been estimated that every known species of plant has five or six species of insects which habitually feed upon it.

We all have heard of the Hessian fly, of the weevil, and of the army-worm. The legislature of Massachusetts has in recent years been spending hundreds of thousands of dollars in the attempt to exterminate the gipsy moth. The caterpillar of the Cabbage butterfly ruins every year material enough to supply sauerkraut to half of the people. The codling moth, the little pinkish caterpillar which worms its way through apples, is estimated to destroy five millions of dollars’ worth of apples every year within the limits of the United States.

A few facts like these serve to show that the study of entomology is not a study which deserves to be placed in the category of useless pursuits. Viewed merely from a utilitarian standpoint, this study is one of the most important, far outranking, in its actual value to communities, the study of many branches of zoÖlogical science which some people affect to regard as of a higher order.