Popular Science Monthly/Volume 51/July 1897/Some Facts About Wasps and Bees
|SOME FACTS ABOUT WASPS AND BEES.|
By Dr. R. W. SHUFELDT.
ONE of the most extensive and at the same time one of the most interesting groups of insects in the entire range of entomology is that order which has been created to contain the ants, bees, and wasps with their numerous allies. This association was called the Hymenoptera by Linnæus, the name having reference to the fact that the anterior and posterior wings of the winged forms are, during flight, connected together by a row, upon either side, of small hooks. This is Kirby's suggestion (Text-book of Entomology, page 103), but it would seem more probable that the word Hymenoptera was derived from the Greek hymen, a membrane, and ptera, wings.
Primarily, this order is divided into the Terebrantia and the Aculeata. In the first named the ovipositor is employed as a borer, while in the second it has become modified into a sting. These two subsections are by various classifiers again divided into several other divisions, and these again into families, genera, etc., as in the case of other natural alliances of animals. Both the habits and structure of the insects included in this group are characterized by great variety, and the majority of its members exhibit an extraordinary amount of intelligence, especially this being true in the case of the ants and wasps. A perfect host of parasitic insects also belong to this group, attacking both the larvae and eggs of other insects. Were all the literature extant that has been devoted to the ants alone got together, it would form by no means a small library; but such a library would be completely overshadowed were it compared with a similar one collected in the case of bees. Of the common honeybee alone, Mr. John Hunter, the late Secretary of the British Bee Keepers' Association, has said: "No nation upon earth has had so many historians as this remarkable class of insects. The patience and sagacity of the naturalist have had an ample field for exercise in the study of the structure, physiology, and domestic economy of bees; their preservation and increase have been objects of assiduous care to the agriculturist; and their reputed perfection of policy and government have long been the theme of admiration, and have supplied copious materials for argument and allusion to the poet and the moralist in every age. It is a subject that has been celebrated by the Muse of Virgil and illustrated by the philosophic genius of Aristotle. Cicero and Pliny record that Aristomachus devoted sixty years to the study of these insects, and Philiscus is said to have retired into a remote wood that he might pursue his observations on them without interruption. A very great number of authors have written express treatises on bees, periodical works have been published relating exclusively to their management and economy, and learned societies have been established for the sole purpose of conducting researches on this subject." When we have such facts as these before us one is enabled to form some estimate as to what the literature of the entire order Hymenoptera would amount to as a whole.
Nor has the historical naturalist neglected the wasps in his labors, for the literature upon these remarkable insects is likewise very voluminous. They constitute the true Hymenoptera aculeata, Kirby using the term Diploptera, dividing them into three families. Of these, the social wasps (Vespidæ) are represented by a number of genera in various parts of the world, containing a host of interesting species. Some of these are of small size, while others stand among the biggest of the entire group. One form found in China and Japan measures two inches across the wings. Many of these wasps sting with great severity, and it has been related of Mitchell, the Australian explorer, that he was stung by a species found in that country, and the pain caused thereby forced him to scream out with agony. It had the effect of temporarily paralyzing his leg, and the great spot on the limb occasioned by the injected poison did not disappear for at least six months. Many wasps are brilliantly colored, while the external structural parts of others are extremely unique. For example, the Masaridæ of Africa and Australia is a family in which the antennæ present a great variety of shapes, some of them even being clubbed, while others are extremely long and slender. Numerous species of wasps and hornets are fossorial by habit, either constructing underground burrows for themselves or else occupying those formed by other insects. Some of these types are very large, some are small, some are solitary by habit, others live in communities. We have one big species of fossorial wasp that I have studied at various points in the Atlantic coast States. Last spring there was a large colony of these established beneath the sweeping limbs of a fir tree near the main entrance to the Smithsonian Institution. The ground in this locality was riddled with their burrows. A great many cases of the sting of this formidable wasp are known to me. Years ago I knew of a case where a passenger upon a Mississippi River boat was stung by one of them on the back of the neck, and the man died eventually from the effect of it. The insect was knocked down on the deck at the time, and was found to be bearing a large cicada in its mandibles.
Some of the smaller fossorial wasps appear like large ants, the females being without wings. They also have a sting, and are clothed with a fine hairy coat, often of a bright yellow or brilliant vermilion. In New Mexico, in sandy places, I frequently saw these insects, but never more than one at a time, and only a few in the course of a day. They have been called "solitary ants" (Mutilla?). There are hundreds of species in the world of these fossorial wasps, some winged, others wingless; some very small, others measure three or four inches across the wings (Pepsis, etc.); while many of them exhibit the most wonderful coloring in metallic blues, greens, reds, and yellow. Nearly all have the habit of paralyzing other insects by stinging them, then carrying their helpless victims to their subterranean nests, where they are buried alive by the side of their eggs, so that when the larvæ are hatched out they find a fresh repast awaiting them in the form of these living but paralyzed spiders, caterpillars, etc. The "mud daubers" have the same habits, and we all know them, and how they, with pellets of mud, build their curious cells against walls and fences and in all sorts of places about our country houses. These are great species to paralyze spiders and place them in these mud cells and sealing them up afterward for the future use of their young (Pelopœus). When collecting in New Orleans I frequently did a good day's work in spider collecting by cracking open these mud nests. Packard also refers to those sand and mud wasps that dig deep holes in our gravel walks and have the instinct to sting grasshoppers in one of the thoracic ganglia, thus paralyzing the victim, in which the wasp lays her eggs; and the young, hatching, feed upon the living but paralyzed grasshoppers, the store of living food not being exhausted until the larval wasp is ready to stop eating and finish its transformations (Sphex ichneumonea).
In a paragraph above I have referred to the family Vespidœ of the group Diploptera, and it includes some of the most interesting wasps and hornets of which we have any knowledge. So far as it is known to me, the Vespidœ are all social species, the individuals consisting of males, females, and neuters. They are also known as the "paper-making" wasps, having the habit of constructing paper nests of various sizes and forms in which their young are reared. Our common brown wasps (Polistes) are too well known to require any detailed description. To those living anywhere in the Atlantic States their paper nests are very familiar, being formed of a circular disk of a single tier of cells, being suspended at the solid back by a median pedicle attached to the point chosen by the community to build. Usually these cells face downward, but occasionally the plane of the nest is vertical or nearly so, causing the long axes of the cells to lie horizontally, or more or less obliquely. This grayish, papery stuff used by the paper-making wasps is a composition of their own manufacture. In the case of the common wasp it is made by the female (Vespa vulgaris), she using the fibers of old wood for the purpose. These she gnaws and kneads until they come to be of a consistence of papier-maché pulp—the mixture being assisted by the secretion of the salivary glands of the insect.
The paper hornet (Vespa maculata) builds often a very large and elaborate nest of this material. These structures are frequently found in various localities in the eastern United States and elsewhere. The year before last a colony of them built beneath the eaves of the tower to my residence in the suburban parts of Washington, D. C. A great paper nest filled the entire angle of the recess. When they build in the forests, however, these insects usually select the smaller limbs of bushes or trees, making the nest more or less spherical or ellipsoidal in contour. Sometimes these are placed high up in the trees, but again may be close to the ground. Two years ago I discovered a deserted one near my present home that was fastened to the twin trunks of a small dogwood, its lower surface being practically in contact with the ground. It was of an egg-shaped form, with the small end downward; the entire affair measuring about thirty centimetres by twenty-two centimetres, selecting for the purpose the greatest vertical diameter and the longest horizontal one (see Fig. 2). Eight distinct layers composed the walls of this nest, and its entrance, a small oval opening, was situated low down in front. It contained three tiers of unipedicled nests of cells, they being closely packed together, and the disks faced downward and were about a centimetre apart. As usual, any single cell was in contact with all its juxta-placed neighbors, and when not too closely crowded they were seen to be of a cylindrical form, but if the crowding was closer they then assumed the hexagonal shape. At their bases they were rounded, while inferiorly they were open and exhibited the various means by which the young had escaped when the proper time had arrived for them to do so. In some cases the thin paper cap was perforated; in others it had been lifted as a cover; while, finally, in some it was practically gone altogether. Paper hornets will, as every one knows who has ever had any experience of the kind, sally forth in numbers and protect their nest by winged attacks en masse and in loose order, their stings being no trifling matter in many cases. I have before
Fig. 2.—Nest of the Paper Hornet (Vespa maculata). One side cut away to show interior. Collected and photographed by Dr. Shufeldt.
me another very pretty nest of this kind found in the same locality, but built by a different species. It is no bigger than an ordinary peg top, being attached to the twig of a blackberry vine by its large end, the apex, looking directly downward, being occupied by a single circular aperture leading to the interior. Externally this little structure is very smooth, and it contains but one small disk, composed of but seven or eight cells.
Other communities of social hornets build their vespiaries in the hollows of trees and logs, which they occasionally clean out to render the places fit for their purposes.
Arthur Shipley, in describing some of the habits of the Vespidœ, has said in part that the workers among hornets "are females in which the ovary remains undeveloped; they resemble the perfect female in external appearance, but are slightly smaller. Unlike the bees', the wasps' community is annual, existing for one summer only. Most of the members die at the approach of autumn, but a few females which have been fertilized hibernate through the winter, sheltered under stones or hollow trees. In the spring and with the returning of warm weather the female regains her activity and emerges from her hiding place. She then sets about finding a convenient place for building a nest and establishing a new colony."
The methods of making the paper cells and their arrangement, the laying of the eggs in them, and the rearing of the young are practically much the same in both the common wasps and the social paper hornets. So Professor Shipley, after describing the manufacture of the paper nest of the common wasp (Vespa vulgaris)—how she lays a single egg at the bottom of each of the first three cells, and then this, the foundress of the society, "continues to add cells to the comb, and as soon as the grubs appear from the first-laid eggs she has in addition to tend and feed them."
"The grubs are apodal, thicker at the middle than at either end; the mandibles bear three teeth; the maxillæ and labium are represented by fleshy tubercles. The body, including the head, consists of fourteen segments, which bear lateral tubercles and spiracles. They have no arms. They are suspended with the head downward in the cells, and require a good deal of attention, being fed by their mother upon insects which are well chewed before they are given to the larvæ, or upon honey. At the same time the mother is enlarging and deepening the cells in which they live, building new cells and laying more eggs, which are usually suspended in the same angle of each cell. The development within the egg takes eight days.
"After about a fortnight the grubs cease to feed, and, forming a silky cover to their cells, become pupæ. This quiescent state lasts about ten days, at the end of which period they emerge as the imago or perfect insect. The silky covering of the cell is round or convex outward, and to leave the cell the insect either pushes it out, when it opens like a box lid, or gnaws a round hole through it. As soon as the cell is vacated it is cleaned out and another egg deposited. In this way two or three larvæ occupy successively the same cell during the summer. The first wasps that appear in a nest are neuters or workers, and these at once set to work to enlarge the comb and feed the larvæ, etc. . . . "In a favorable season, when the weather is warm and food plentiful, a nest may contain many thousands of cells full of wasps in various stages of development, and, as each cell is occupied two or three times in the course of a summer, those authorities who put the number of the members of the community as high as thirty thousand are probably not far wrong.
"At the approach of autumn the society begins to break up; the males fertilize the females while flying high in the air; they then die, often within a few hours. The workers leave the nest, carrying with them any grubs that remain in the cells, and both soon perish. The nest is entirely deserted. The females which have been fertilized creep into crevices under stones or trees or hide among moss, and hibernate until the warmth of the following spring induces them to leave their hiding places and set about founding a new community."
Where hornets or wasps occur in very large numbers they frequently, at certain seasons, do considerable damage to fruit and forest trees by gnawing off the bark to build their paper nests. They destroy the fruit they attack, living as they do upon the juices extracted from it. But, on the other hand, these insects are very useful in that they likewise feed on flies and other insects, and so very materially diminish the numbers of these pests. Some wasps live in part upon honey, which they collect from the most open-petaled flowers, and thus to a very moderate extent they may be regarded in the light of flower fertilizers. Kirkland says, in the first volume of the American Naturalist, that "the paper hornet (Vespa maculata) often enters my nucleus hives, when I am rearing Italian queen bees, and captures the young queen in the midst of her little colony, usually just after she has commenced her first laying. I have seen this depredator enter the small hive, drag out the queen, and fly away with her to the woods" (page 52). Some of the species of the genus Polistes store up honey which is poisonous, from the fact that it has been collected from poisonous flowers. They are found in South America, where also species of the genus Chartergus occur—wasps that make a very remarkable and tough nest, with funnel-shaped combs inside, arranged one inside of another, nest fashion, but not in contact except at their points of suspension. At the apices of these cones occur the apertures of entrance for the inmates to pass up among the conical tiers. Icaria, a genus represented in Australia, the East Indies, Africa, and Madagascar, contains some very remarkable species. Some of them have the power of contracting the hinder segments of the abdomen so far within the body that at first sight they appear to have been broken off. Many of these species are very small and brilliantly colored, and often build curiously shaped little paper nests. Wasps and hornets are not without their enemies, for their nests are frequently infested by parasitical insects that feed upon their grubs. According to Shipley, "In the tropics some species are attacked by fungi, the hyphæ of which protrude between the segments of the abdomen and give the wasp a very extraordinary appearance."
From the wasps and hornets I next pass to a consideration of a few of the species of bees, omitting, however, anything in reference to the common hive bee (Apis mellifica), of which insect entire volumes have been written.
Hundreds of species of wild bees are now known, and they are to be found in almost every part of the world, and doubtless many species yet remain to be described by the entomologists. Those found have been arranged in the two families Andrenidœ and Apidœ by Kirby, and are subdivided into a number of genera. In the first family all the species are solitary of habit, while in the second both solitary and social species are found. True honey-bees are found wild in this country, and the species most nearly allied to them with us is the common bumblebee (Bombus), of which genus upward of fifty species or more occur in North America. This bee, or rather a queen of this species, hibernates all winter, but early in the spring makes her nest. This may be under any old log or piece of turf or the vacated nest of a field mouse. A dozen eggs or so are laid in a mixture she makes of pollen and honey, and the young appear in series from egg to imago, the period of development being of no great length. From this time on the study of the colony is full of interest, but the sequence of events is not altogether unlike what has been described above for the wasps, the nature of the nest and the fate of the eggs when first deposited being the main difference.
Bumblebees are preyed upon by a variety of parasites, the most curious being a species of Apathus, an insect so closely resembling its host that it requires the eye of an expert to detect the one from the other. Many of us are familiar with the history of the tunnels in posts, planks, and similar places made by that large species known as the Virginian carpenter bee (Xylocopa virginica); and then, too, we have its pretty little ally, the bright pea-green Ceratina dupla, that constructs similar tunnels in such plants as have a pithy center, as reeds and elderberry bushes. These tunnels in either case are intended to hold the cells in which the eggs are deposited and the young reared. The habits of the tailor or leaf-cutting bee are even still more interesting (Megachile centuncularis). They have strong, sharp-cutting jaws, by means of which they cut away bits of leaves to be used in the formation of their cells, the site of the nest being in elder stalks or under planks or in the hollows of certain trees. Their very interesting habits have been closely studied by a number of naturalists. Mason bees of the genus Osmia are also small and brilliantly colored, blue or green, having habits somewhat akin to those of Megachile. A European species is said to build her cells of mud, depositing them in the empty shells of snails. Many other species of this genus Osmia, in various parts of the world, possess habits full of interest to us, that have been described in the books with greater or less detail. Then we have the less intelligent types of those bees that burrow in the ground, that are solitary, and leave their young to look out for themselves. These fossorial bees see their types in such forms or species as the common Andrena vicina, that I have observed in many parts of New England. Parasitic bees, called cuckoo bees (as Nomada sex-fasciata), prey upon these fossorial forms, such as Andrena or its allies of the genus Halictus and others, by laying their eggs in their nests. They are also infested by numerous other parasites, such as by certain ichneumon flies and oil beetles (Meloë), and others. Some of the South American bees are destitute of stings (Melipoma, Trigona), and I have frequently seen a large bee here near Washington that does not sting. It has the appearance of a Bombus, but the fore part of the head is nearly all of a very pale yellow, almost white.
Carder bees (Bombi muscorum) are known to all frequenters of open fields and meadows, after the haying season has commenced. A popular writer at hand says: "They select for their nest a shallow excavation in the ground about a foot in diameter, or, if such a one is not to be found, they make one with prodigious labor. This they cover over with a dome of moss, or sometimes with withered grass. They collect their materials by pushing them along upon the ground, working backward like the tumblebugs. Frequently in the spring a single female founds a colony, and by perseverance collects the mossy covering in the way described; later in the season, when the hive is populous and can afford more hands, there is an ingenious division of this labor, A file of bees, to the number sometimes of half a dozen, is established from the nest to the moss or grass which they intend to use, the heads of all the file of bees being turned from the nest and toward the material. The last bee of the file lays hold of some of the moss with her mandibles, disentangles it from the rest, and, having carded it with her fore legs into a sort of felt or small bundle, she pushes it under her body to the next bee, who passes it in the same manner to the next, and so on till it is brought to the border of the nest—in the same way as we sometimes see sugar loaves conveyed from a cart to a warehouse by a file of porters throwing them from one to another. The elevation of the dome, which is all built from the interior, is from four to six inches above the level of the field. Besides the moss or grass, they frequently employ coarse wax to form the ceiling of the vault, for the purpose of keeping out rain and preventing high winds from destroying it. Within this retreat the eggs present an appearance not very different from that of the bumblebee."
In conclusion, I may say that among the ancient Hebrews and Romans the error was widely credited that bees made their nests and reared their young in the carcasses of dead animals; and, although these people knew that bees were governed by a ruler, they labored under the impression that it was a king and not a queen. Such ignorance can easily be overlooked, however, when we come to consider that it is only of comparatively recent date that we have worked out the biology of these insects, and, as it is, there yet remains the greater part, by all odds, of their natural history of which we know little or absolutely nothing, and to which must still be added that of the host of species of this order yet to be discovered and made known to science.
- From the Greek diplos, doubled, and ptera, wings, referring to the fact that the representatives of this family, when in a state of repose, fold their fore wings longitudinally.