 Section 5 of THE SCIENCE HISTORY OF THE UNIVERSE, VOLUME 6 Chapter 4 The Higher Invertebrates, Part 1 It seems natural to think of a spider or scorpion as an insect, but in fact they are not true insects, although they belong to the arthropod series of invertebrates. All insects have three pairs of legs and breathe by tracheae. Spiders and scorpions have four pairs of legs and breathe by lung books, and apparatus like modified gills. And in all the details of their anatomy, spiders and scorpions are as different from insects as they are from crustaceans. All insects, accepting perhaps a few unimportant primitive kinds, have wings or have had them at a former period in the development of the race, although in many groups the wings are degenerate or lost. Scorpions and spiders appear never to have developed wings at all. In short, the insect class may be regarded as an adaptation of the arthropod invertebrates to aerial life, the spider class to terrestrial life, the crustaceans to marine life. Each in its own element has had a long and more or less successful career. Each has made attempts to invade the territory of the others. For in the West Indies and other oceanic islands are crabs which pass their life mostly on dry land, and the spider swinging in air from a slender thread, and even in some cases traveling through the air on a long film of unattached gossamer, is emulating the habits of the flying insect. But the insects alone have invaded the alien habitats with any great success, and so far as terrestrial life is concerned, they have crowded the spiders and scorpions to the wall. Scorpions are found only in tropical countries and are distinguished by the elongate tail with venomous tip and the large clawed grasping legs in front. They have four pairs of walking legs like spiders. In the old natural history books, they are credited with committing suicide when unable to escape by stinging themselves to death. Unfortunately for the story, aside from the argument that the mental processes of the lower animals are not very likely to lead them to deliberate suicide, the feat is anatomically impossible. And if it were possible, the poison would have no effect. Spiders are common everywhere, and like scorpions they are all carnivorous, sucking the juices of insects which they capture. Many of them, but not all, form webs, and the construction of the web is a remarkable piece of engineering, which must involve highly elaborated instincts comparable only to those of the higher insects. The material of the web is a liquid silk secreted by the spinning glands and forced through the fine tubes of the spinnerettes, hardening immediately on exposure to the air. The spun threads are used also to line the nest, to envelop the cocoon, and to assist the spider in his aerial gymnastics. The spiders are by no means confined to webs, but certain of them construct more permanent dwellings. Thus the mason spiders dig a hole in the ground and then spin across and across the mouth of it, a woven door with a hinge at one side. Even less known and more curious is the work of a little water spider, who, not desiring to forego the power of air-breathing, spins a silken diving-bell wherein is imprisoned a globule of air. Mild spiders are very much smaller than the females, the difference in bulk being sometimes as thirteen hundred to one, and more brightly colored. With spiders and scorpions are classed various parasitic insects such as mites and ticks and other minute and degenerate forms. The king crab or horseshoe crab has also been discovered to be more nearly related to the arachnoids than to the crustaceans, which it resembles in appearance and habitat. And another group of aquatic animals, the eurypterids, now extinct, is regarded as most nearly related to the scorpions among living animals. The eurypterids inhabited brackish or fresh water during the Paleozoic era, and some of them attained a length of six or seven feet, a truly formidable size for that ancient period. The numbers and variety of insect life are far beyond those of any other animals, at least upon the land. More than half the described species of zoology are insects. More than three-fourths of the land animals belong to this class. And the innumerable hosts of some sorts make them, despite their small size, the most dreaded and dangerous enemies with which man has to contend. The seriously noxious insects are indeed a small minority. Most are indifferent so far as man's welfare is concerned. A few are actively beneficial. But as a class it must be affirmed that the harmful activities of insects outweigh their beneficial action. They are rivals with man for the possession of the fruits of the earth, and if to the damage on this score be added their activities as carriers of infectious diseases, they may well be regarded as the most formidable enemies of man in the animal kingdom. The insect is an evolution from the primitive worm or anilid type, adapted to terrestrial life as the crustacean is to marine life. And the structure and plan of organization is much the same in both. There are two most important differences. The first of these is that the crustacean breathes by gills, the insect by tracheae, branching tubes which ramify into every part of the body, and by expanding and contracting, taken fresh and expel vitiated air as do our lungs. The second difference is that the insect has wings, generally four of them. The arrangement of the nervous system, the circulation, the appendages and mouth parts, the sense organs and the alimentary system are much as in crustaceans. In comparison with higher vertebrates of the land, the insect shows a fundamentally different plan of organization. Thus, in a vertebrate the principal nervous system is along the dorsal, in an insect along the ventral side of the animal. In a vertebrate the jaws open up and down, and the teeth are originally modified scales. In an insect the jaws open sideways, and the teeth are modified legs. In a vertebrate the skeleton is internal, in an insect it is external. The heart of a vertebrate is in its thorax, the stomach in its abdomen. In an insect the position is reversed. The vertebrate pumps vitiated blood from the tissues to the lungs to be aerated. The insect pumps fresh air to freshen the vitiated tissues directly. The wings of a bird or a bat are modified legs. The wings of an insect are outgrowths from the skin of the back, and so on throughout. The resemblances between insects and land vertebrates are mostly superficial. Their plan of organization is wholly different, and the similarity is due to both being adapted to live on land. The resemblances between insects and crustaceans indicate relationship. Their plan of organization is fundamentally the same, the differences being due to adaptation to terrestrial life in one, to aquatic life in the other. Note that there are water insects and likewise land crustaceans, but the land crustaceans still breathe by gills, a method evidently adapted for water breathing. And the water insects are dependent upon air for breathing, so that they have to come to the surface from time to time at least. The most important feature of the development of the higher orders of insects is the metamorphosis or change of form from larval to adult. The egg hatches into a larva wholly different from the adult in form, internal organs, and manner of life, and the larva in changing to the adult form undergoes a metamorphosis which involves the almost complete breaking down of all the structures of the body into a mass of formless tissue, and the rebuilding out of this formless tissue the organs and parts proper to the adult. This extraordinary change takes place in from two or three days to several weeks, and the insect undergoing it is called a pupa. In the lower orders of insects there is no metamorphosis or a very incomplete one. The meaning of this change and the object of it in furthering the interests of the insect is not very clear. Obviously, the wingless crawling larva may be regarded as having once represented the ancestral type from which the insect is descended, but as now greatly altered to fit the requirements of its own juvenile habits and environment, and it is possible to explain the breaking down of the old tissues into a formless mass of cells by supposing that larva and adult have each proceeded so far on their divergent specializations of structure and form in adaptation to the needs of each, that it has become cheaper, so to speak, to break down the old tissues and build anew, rather than to modify the old into the new tissues along the lines of natural development. Seeing aside certain primitive wingless insects, the three orders, ephemerida, placoptera, and odonata, mayflies, stoneflies, and dragonflies, are given lowest rank among insects because of their incomplete metamorphosis. All of them haunt the freshwater ponds, rivers, or streams wherein their larvae well, and are not seen far away from water. The larvae are at first wingless, provided with gills instead of spiracles, so that they are not obliged to come to the surface. They develop rudimentary wings during their larval life and change to the adult form by a succession of molds, like crustaceans, without any breaking up of the internal structures. The dragonflies are unexcelled among insects, says Kellogg, for swiftness, straightness, and quick angular changes in direction of flight. The successful maintenance of their predatory life depends upon this finely developed flight function, together with certain structural and functional body conditions, which might be said to be accessory or auxiliary to it. All have four well-developed wings. The body is long, smooth, and subcylindrical, or gently tapering. This clean, slender body offers little resistance to the air in flight and serves as an effective steering oar. The wings are long and comparatively narrow, four and hind wings being much alike. The head is unusually large and more than two-thirds composed of the pair of great compound eyes. More than 30,000 facets have been counted in the cornea of certain dragonfly species. For accurate flight and successful pursuit of flying prey, the dragonfly has full need of good eyes. The jaws are strong and toothed and obviously well adapted for tearing and crushing the captured prey. When the prey is come up with, however, it is caught not by the mouth, but by the leg basket and then held in the forelegs while being bitten and devoured. The internal anatomy is specially characterized, as might well be imagined, by a finely developed system of thoracic muscles for the rapid and powerful motion of the wings and the delicate and accurate movements of the legs. The respiratory system is also unusually well developed. The prey of the dragonfly may be almost any flying insect smaller than itself, although midges, mosquitoes, and larger flies constitute the majority of the victims. The good that is done by dragonflies through their insatiable appetite for mosquitoes is very great. Now that we recognize in mosquitoes not only irritating tormentors and destroyers of our peace of mind, but alarmingly dangerous disseminators of serious diseases—malaria, yellow fever, filariasis—any enemy of them must be called a friend of ours. Dragonflies are a very ancient race of insects. They tenanted the strange antique forests of the coal period, and some were for an insect of gigantic size, one having a spread of wings of nearly two feet. Others are found in the still older forests of the Devonian, and indeed it is to the ancient life and ancient land that dragonflies seem peculiarly appropriate. The dark somber tropical swamp forests of those early days, their trees, gigantic club mosses, ferns, and horsetail rushes, before the appearance of flowers, of broadleaved trees, of land vertebrates, seem peculiarly fit to be tenanted by insects which today are associated with similar life conditions, and which have no relations with flowering plants or with the higher developments of insect life. The various kinds of bugs, scale insects, and plant lice, which make up the order of the hemiptera, or bugs, have the mouth parts modified into a sucking beet. They feed upon the juices of living plants, or the blood of living animals, and include the worst of insect scourges. Owing to their sucking habits, they are more difficult to combat than the biting insects, and their fecundity is enormous. The order hemiptera, says Kellogg, includes over 5,000 known species of North American insects, representing a large variety and a great economic importance. Some of the most destructive crop pests and most discomforting insect scourges of man and the domestic animals belong to this order. The chinchbugs' ravages in the corn and wheat fields of the Mississippi Valley offer effective evidence to the dismayed farmers of the workings of a displeased providence. The tiny sap-sucking aphids and phylloxera and insignificant-looking scale insects make the orchardist and vine-grower similar believers in supernatural moral correction by means of insect scourges. And the piercing and sucking lice and bugs in the English meaning make personal and domestic cleanliness a virtue that brings its own immediate reward. The name hemiptera is derived from the character of the four wings shown by most, though by no means all of the members of the order. This is the thickening of the basal half of the otherwise thin, membranous wing, so that each four wing is made up of two about equal parts of obviously different texture and appearance, hence half-winged. All hemiptera, except the male scale insects, have an incomplete metamorphosis, the young at birth resembling the parents in most essential characteristics except size and the presence of wings. By steady growth, with repeated multings and the gradual development of external wingpads, the adult form is reached, without any of the marked changes apparent in the insects of complete metamorphosis. With similar mouth parts, the young have, in most cases, similar feeding habits, preying upon the same kinds of plants or animals that give nourishment to the parents. The extent of the injuries done by various members of this order to farm and orchard crops, to meadows and forests, and to our domestic animals is enormous. Of the other insects, the order of beetles includes numerous crop pests, and the caterpillars of many moths and a few butterflies do much damage. Locusts have a healthy appetite for green things, and many kinds of flies could be lost to the world to our advantage, but perhaps no other order of insects has so large a proportion of its members in the category of insect pests. The single hemipterous species, Blissus lucopterus, better known by its vernacular name of chinchbug, causes an annual loss to grain of twenty millions of dollars. The grape phylloxera destroyed the vines on three million acres of France's choicest vineyards. The San Jose scale has in the last ten years spread from California to every other state and territory in the United States and become a menace to the whole fruit growing industry. So, despite their small size and their general unfamiliarity to laymen, the hemiptera are found by economic entomologists in their warfare against the insect scourges of the country to be one of the most formidable of all the insect orders. Remedies for sucking insects are not readily found. Kerosene emulsion is the one chiefly employed. Fumigation or spraying with tobacco is effective on a small scale, and for scale insects, when the leaves are off the trees, hydrocyanic acid fumigation or lime sulfur salt spraying are used. The orange scale has been successfully held in check by importing and fostering a ladybird beetle which feeds upon it, and the chinch bug by introducing a parasitic fungus which kills the bugs by wholesale when the weather conditions favor its spread. The order orthoptera includes the cockroaches, locusts, grasshoppers, and crickets, all familiar types of insects, many of them of large size and several ranking among the important noxious insects. On the other hand, their active leaping and noisy flight, their cheerful trilling and chirping lend a variety and interest to outdoor life which one might sadly miss if deprived of their companionship. Their music is rather instrumental than vocal, since it is made by rasping the wings against each other or against the roughened inner surface of the thighs. In all this order, the mouth parts are modified for biting, and they mostly live on vegetable food, especially upon green leaves. In the grasshoppers, locusts, and crickets, the hind limbs are modified for leaping. The cockroaches, praying insects, and walking sticks are walking or running types. The roaches are one of the most ancient and persistent groups of insects. They shared with the dragonflies the dominance of the ancient forests of the coal period, and are today a familiar household pest, especially in tropical countries and aboard ships. The mantis or praying insect is a carnivorous type, feeding upon flies or other insects which may come within reach, and its curious attitudes have caused a variety of fanciful or superstitious legends to gather around it. To kill a mantis is very generally considered sinful or unlucky, and among the quaint, monkish legends is one of Saint Francis' savior, who, seeing a mantis moving along in its solemn way, holding up its two forelegs as in the act of devotion, desired it to sing the praise of God whereupon the insect caroled forth a fine canticle. The most singular of the orthopterous insects are the walking sticks, which mimic the green twigs and stalks of grass among which they live, in form, color, and characteristic attitudes so closely that they are one of the best examples of protective mimicry. The swarms of locusts, which from time to time descend upon cultivated agricultural regions, devouring every green thing in their path, and bringing ruin and desolation to the farmer, are now known to be normally inhabitants of the high-lying grassy plains, driven from their accustomed feeding grounds by exceptionally dry seasons which have withered and destroyed the grass of the high plains. They cannot maintain themselves permanently in the moist climate of the low-lying valleys, and for their periodical incursions there is little remedy except to fight them in the high-dry plains which are their natural home. The termites, or white ants, are quite unrelated to the true ants, and quite unlike them in appearance. They belong to the lower orders of insects. The young are like the adult from the time they emerge from the egg and do not undergo any metamorphosis. But, like the ants, they have an elaborate social organization and live in great colonies, mainly composed of sterile workers of several castes. Among the ants, bees, and wasps, these sterile workers are always females. With the termites, they are of both sexes. The colony is presided over by a royal pair whose functions are confined to egg-laying. As with the ants, the workers are wingless, and the fertile males and females are winged only during the swarming season when they leave the nest to found new colonies. Termites live upon dead wood, and are abundant mainly in tropical or subtropical regions, where they are fearfully destructive to all wooden buildings, furniture, etc., except they be constructed from some of the few kinds of wood that are immune to their attacks. The great hillock nests which they construct are a prominent feature of the landscape in some parts of tropical Africa. Their habits and complex social organization are almost as remarkable as those of the ants, but the communal instinct is not quite so strongly developed. And, of Section 5. Section 6 of The Science History of the Universe, Volume 6. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. The Science History of the Universe, Volume 6, edited by Francis Rolt Wheeler. Zoology, Chapter 4. The Higher Invertebrates, Part 2 With the beetles, or colioptera, begins the series of higher insects with complete metamorphosis. That is to say, the young develop from the egg into a larva quite unlike the adult in form, structure, and habits, wingless and more or less worm-like in appearance and habits. After a period of active growth, the larva becomes quiescent, wrapping itself up usually in a cocoon or protective case, and undergoes a remarkable change, the organs and tissues of the body being largely broken down and reformed, and finally the completed insect, or imago, issues from the cocoon or cell, perfect in form and widely different from the larva, not merely in its external form, but in the whole internal structure as well. This extraordinary change, which has often been used as an apt natural illustration of ethical regeneration, is one of the most striking and wonderful features of insect life. It is completely carried out in the beetles, moths, and butterflies, the lace-winged flies, the two-winged flies, and in the ants, bees, and wasps. The lower orders of insects exhibit various degrees of approximation toward it, but in none of them is it complete. The beetles include a vast multitude of different species and genera. Twelve thousand species are known from the United States and Canada alone. All of them are distinguished by the hard, horny four-wings, which serve as a sheath for the membranous hind-wings, these alone being used for flight. The body is compact in form, covered by hard, horny skin, and the mouth parts are adapted for biting, the jaws often strong and large. Some beetles are predacious, others, and these the great majority, are plant-eaters, and some of them are notorious pests. Among the noxious beetles may be especially noted the potato bug, wireworms, white grubs, and other beetle larvae, fruit and grain weevils, apple tree borers, and a host of less important ones. The predacious beetles, on the other hand, are actively beneficial by destroying quantities of noxious insects. Among the handsomest members of the order are the tiger beetles and the various predacious ground beetles, active, alert, many of them, of bright metallic color patterns. Many beetles, like the fireflies and glowworms, are luminous at night. Some of the tropical fireflies emit light enough to read by when a few of them are placed under a glass. The stag beetles and rhinoceros beetles are among the largest of a group, lamellicornia, notable for the huge mandibles and various peculiar, horn-like processes developed in the males of many of the species. The numerous kinds of wood-boring species, some of them of giant size, do serious damage to orchards and forests. The little round ladybird beetles, or ladybugs, with their polkadot pattern of red and black, on the other hand, are a great help to the gardener and fruit raiser, as they feed upon plant lice and scale insects. In the large group, which includes the curculios, weevils, and snout beetles, the front of the head is prolonged into a long beak, at the tip of which are the small, sharp jaws. Many of these also are serious insect pests. The diptera, or two-winged flies, includes gnats, mosquitoes, and the innumerable kinds of true flies, an immense group, including some fifty thousand species, many of them familiar from the annoyance they inflict on men and animals, and in recent years more seriously considered as carriers of disease. The mouth parts in all are adapted for sucking and piercing, and they have but two wings, the hindre pair being converted to little structures which are used to balance or direct the fly in his flight. The mosquitoes are familiar from the tropics to the poles, but it is only in recent years that their relations to three serious diseases of man have been suspected and proved. It has been shown beyond question that the germs of malaria, yellow fever, and filariasis are transmitted from man to man through the agency of mosquitoes. The life history of the malaria germ has been quite thoroughly investigated. Malarial fever, which is the most deadly disease of the tropics, is caused by a minute amoeba-like, one-celled organism, parasitic in the blood corpuscles. These grow and multiply asexually in the human blood, but their sexual multiplication occurs within the stomach cavity of the mosquito anopheles. Thence they make their way to the poison gland of the insect and are so introduced into the body of the next person bitten by this species. The anopheles is the mosquito with spotted wings, fortunately less common than the gray winged or brindle-winged mosquitoes of the genus Culex. Another mosquito, stegomia, is responsible for the dissemination of yellow fever and of filariasis. The life history of the germ proceeding along much the same lines as with the malaria germ, so far as it has been investigated. The destruction of mosquitoes, especially of the anopheles and stegomia, and protection from their attacks have consequently been recognized as a most important safeguard to health, especially in tropical countries. Protection is chiefly to be had by extensive and thorough screening of houses and porches. Destruction of the mosquito larvae can be effectively accomplished by draining swamps and stagnant pools in which they chiefly breed, and where draining is impossible by periodically covering the surface of the water with a thin film of kerosene. Standing water in cisterns or rain barrels should be carefully screened. By these methods of prevention, the mortality from malarial fever and yellow fever in tropical regions has been greatly reduced when, as in the construction of the Panama Canal, they have been systematically and thoroughly applied. The smaller gnats and midges are nearly related to the mosquitoes and are equally oppressed throughout the world from their blood-thirsty habits. The compact, heavy-bodied flies with short and tinny are a much larger group than the mosquitoes and many of them attain large size. The great majority are harmless to man, a few beneficial as they prey upon noxious insects, but some do serious injury to growing crops, the larvae or maggots feeding upon the leaves or roots of the plants. A few, such as the bot flies, are parasitic upon animals or man, and others, like the house flies, blow flies, and their allies, are annoying and disgusting pests and dangerous spreaders of disease. The agency of the housefly in disseminating typhoid fever in cities and camps has been properly appreciated only in recent years. Dr. L. O. Howard has recently suggested that, in view of its activities in this direction, it might most appropriately be called the typhoid fly. This fly breeds in stable manure and other decaying matter, and thorough cleanliness and sanitation has already accomplished wonderful results in reducing the death rate from diseases which are largely spread through its agency. Related to the flies, although given a separate ordinal rank, are the fleas, degenerate blood-sucking parasites of mammals and birds, which likewise take part in the dissemination of certain diseases. They are wingless with peculiarly compressed bodies and mouth parts adapted for piercing and sucking. The moths and butterflies, order Lepidoptera, are the insects, says Kellogg, most favored of collectors and nature-lovers. A German amateur would call them the Lieblings Insecton. The beautiful color patterns, the graceful flight, and dainty, flower-haunting habits, and the interesting metamorphosis in their life history make them very attractive, while the comparative ease with which the various species may be determined, and the large number of popular as well as more technical accounts of their life, which are accessible for information, render the moths and butterflies most available among all the insects for systematic collecting and study by amateurs. This great group of insects ranks with the beetles and flies in abundance and variety. Between six and seven thousand species are found in North America alone, but they are even more numerous and varied in tropical regions. They attain their greatest size and beauty of color and pattern in the equatorial forest regions, especially in South America. The exquisite color patterns are due to the covering of minute scales over wings and body. The scales, which are to be regarded as modified hairs, vary in shape and size from one 350th to 130th inch, and their brilliant metallic colors are mainly due to diffraction of light from their finely striated surfaces, while the black, brown, yellow, and dull red colors are due to pigment color in the scale itself. In this group are to be found the most striking examples of protective coloration, of warning colors, of mimicry, and other more obscure phases of adaptive coloration. The Lepidoptera all undergo a complete metamorphosis, and their caterpillars are more familiar objects than the larvae of any other group of insects, as they live mostly on green leaves and are active and voracious feeders. Owing to their habits and numbers, many of the larvae rank among the plagues of farmer, gardener, or tree grower. The adults, mostly nectar-sipping, are harmless as they are often beautiful. The silk moth, from whose cocoons the world's supply of silk is obtained, is also of high economic importance. The annual production of raw silk is estimated at over $100 million. Yet this is, but small, probably, compared with the total amount of damage done to gardens, orchards, and fields by the depredations of the various caterpillars of one kind or another. Among butterflies, the palm is generally given to the giant morphos and their relatives, whose brilliant metallic colors brighten the gloomy recesses of the Brazilian forests. These, like many other inhabitants of the deep forest, habitually fly far above the ground among the treetops and are consequently more difficult to secure. In temperate climates, the swallow-tailed butterflies, papillio, and its relatives are the most widely admired. One of the most familiar of the larger butterflies is the monarch, which owes its success in life partly to its secreting and acrid, ill-tasting fluid that causes birds to let it severely alone. This butterfly is closely mimicked by another, the viceroy, which is not ill-tasting, but doubtless prophets by this resemblance in escaping the attacks of birds. The order hymenoptera, in which are included ants, bees, and wasps, is the most interesting group among all the lower animals, because many of its members have a highly complicated and elaborated communal life. The study of these great insect societies, of their social life, habits, and instincts, is one of the most interesting subjects in the whole range of natural history. From the days of Solomon, the tireless industry and frugality of the ant have been proverbial. The busy ways, the complicated and orderly activities of the bee are familiar to everyone, and metrolinks brilliant and sympathetic description of the life of the great bee communities in his The Life of the Bee, although perhaps too much tinged with the natural tendency to interpret it in terms of human reason and sensations to be wholly reliable, is one of the most fascinating chapters of natural history ever written. Besides these better-known social insects, the hymenoptera include a variety of solitary forms, saw flies, gall flies, and dic-numans, and among the bees and wasps there are all degrees of social organization, from solitary to highly elaborated social types. It is especially through the study of these various grades of organization that an understanding can be obtained of the true meaning of many features of the social life of ants and bees, and of how they were developed. In order to appreciate the character and limitations of their social life, it is necessary first to get some insight into the nature of this intelligence. The nervous system in insects and crustaceans consists of a double cord on the ventral side of the body with paired nodes or ganglia at each segment from which the nerves are distributed, and a pair of principal ganglia on the dorsal side of the head connected with the ventral system by a ring of nerve fibers encircling the gullet. In the higher insects, the dorsal ganglia of the head are expanded into a small mass which corresponds in the main with the brain of the higher animals, but the ventral ganglia also perform part of the functions which in the vertebrates are concentrated in the brain, and the relative size and complexity of the brain mass in insects is by no means to be compared with any of the higher vertebrates. The deficiency is especially in the parts corresponding to this cerebrum lodging the higher intelligent and reasoning powers, the automatic and instinctive acts being governed mainly by the enlarged ventral ganglia. So far as can be judged, the nervous system of an insect is that of a very elaborate and perfect animal automaton, but not much more. It is natural to suppose on seeing the complex and varied activities of an ant or bee community that these insects must possess an intelligence comparable with that of man rather than of the lower animals, and ideas of their life are apt to be colored by this view, but the most eminent modern authorities on their psychology, among whom Professor Forell may be especially mentioned, believe that while not devoid of intelligence, their actions are in the main instinctive and automatic, and that even their intelligent action degenerates into habit, that is, tends to become automatic much more rapidly than in higher animals. The extreme complexity of these instincts can be better understood if it is remembered that the insects are a very ancient group. Little of their early history has been definitely ascertained, but the lower orders of insects, at least such as cockroaches and dragonflies, appeared far back in the age of invertebrates almost as early as the beginning of the geologic record, and the higher orders are known to have existed at a time when highest vertebrates had not advanced beyond the modern salamanders and newts. During the millions of years since that time, while the vertebrates were slowly developing an intelligent brain, the higher insects were elaborating an instinct brain. The most serious difficulty in understanding the actions of insects is that their senses are so different from those of man. Broadly speaking, indeed, they make use of the same media of communication with the outer world. All of them have organs sensitive to ether rays of light and heat, corresponding to human eyesight and to the sense of heat and cold. Most of them have apparatus to sense the waves of sound, although less developed than the ears of vertebrates and different in mechanism. All of them have organs for perception of solid bodies and of the minute particles given out from them, corresponding to the senses of touch, taste, and smell, but differently situated and combined, and generally much more elaborated. The antennae of insects are sensitive to touch and odor, and in most of the higher insects are highly specialized organs. In the ants especially, they usurp the place which in most animals is taken by the eyes. Picture to yourself, says Forel, an old factory sense that is to say a chemical sense effective at a distance and, like our sense of smell, capable of receiving impressions from particles of the most diverse substances diffused through the atmosphere, located not on your nostrils, but on your hands. For of such a nature is the position of the old factory sense on the antennae club of the ant. Now imagine your old factory hands in continual vibration, touching all objects to the right and to the left as you walk along, thereby rapidly locating the position of all odoriferous objects as you approach or recede from them, and perceiving the surfaces both simultaneously and successively as parts of objects differing in odor and position. It is clear from the very outset that such sense organs would enable you to construct a veritable odor chart of the path you had reversed and one of double significance, one a clear contact odor chart restricted to be sure to the immediate environment and giving the accurate odor form of the objects touched, round odors, rectangular odors, elongate odors, etc., and further hard and soft odors in combination with the tactile sensations, to a less definite chart which, however, has orienting value for a certain distance and produces emanations which we may picture to ourselves like the red gas of bromine which we can actually see. If we have demonstrated that ants perceive chemical qualities through their antennae, both from contact and from a distance, then the antennae must give them knowledge of space, if the above formulated law is true, and concerning this there is little doubt. This must be true even from the fact that the two antennae simultaneously perceive different and differently odoriferous portions of space. They must therefore also transmit perceptions and topographically associated memories concerning a path thus touched and smelled. Both the trail of the ants themselves and the surrounding objects must leave in their brains an odor image of immediate space, and this must render associated memories possible. Thus an ant must perceive the forms of its trail by means of smell. This is impossible at least for the majority of the species by means of the eyes. It will appear therefore that this antennal sense which Forel designates as topographical is the principal means by which the brain of the ant is placed in communication with the outside world, supplying the space and form perceptions in the same way that a vertebrate's eyes do. Light and darkness are indifferent to an ant, so far as getting about is concerned. Many of the species use their eyes, but do not depend primarily on them. Others are blind or nearly so. This topochemical sense is present in other insects to a varying extent. In bees and wasps it is well developed, although not to the exclusion of sight as in ants. In flies and dragonflies, and in most of the lower insects, it is more or less rudimentary. They depend chiefly upon the eyes. There are other wide differences in the external sense organs of the various insects from man and from each other. Insects see colors differently. They hear sounds to which the human ear is not sensitive, while they are deaf to tones that it perceives. Their world of perceptions is so different in its nature and its limitations that it is difficult to enter very far into the psychology even of their simplest sensations. For the most part, the facts can only be related as they appear. The ever-present temptation to interpret the actions of an insect in the terms of the observer's sensations is almost sure to lead him astray. In most of the lower animals the young are well able to take care of themselves. In general, they develop from the egg with little or no help from their parents. But in the hymenoptera, as in birds and mammals, the young are helpless larvae unable to forage for themselves and requiring to be supplied with food or fed directly by the adults. This is the most important fact in the life history of these insects. It differentiates them as of distinctly higher type than any other invertebrates, and it is around the care of the young that their social life chiefly centers. It has been well observed that in man the duration and helplessness of infancy is in direct proportion to the progress of civilization. It is equally true of the lower animals that those in which the young require and obtain the help of their parents in their early life are thereby enabled to reach a higher stage in development than those in which the young can and do shift for themselves from the time they emerge from the egg. All of the hymenoptera make provision in one way or another for their young, and the extent to which this care is carried is the index of development in the different groups. The sawflies, the lowest member of the group, merely place the eggs in favorable spots on the stems of plants where the larvae can feed readily upon the juices of the plant. These larvae are little more helpless than true caterpillars and feed in much the same way. The gallflies show the next stage in progress. The eggs are laid in the leaves or stems of various plants in such a position that the irritation of their presence stimulates the plant to develop abnormal growths or galls which are utilized as food by the larvae. The ignuman flies lay their eggs in the bodies of caterpillars, and the larva develops at the expense of its unfortunate host. A great variety of the lower hymenoptera are parasitic in this way upon other insects of various orders, and the parasitism has entailed more or less degeneracy. The life histories of these various parasitic forms form a very curious and interesting chapter in natural history. End of Section 6. Section 7 of The Science History of the Universe, Volume 6. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Melanie Young. The Science History of the Universe, Volume 6. The Study of the Habits of Solitary Wasp and Bees, and the Transitional Forms Between These and the Social Kinds, give the clue to the method of development of these great insect societies, and helps to explain many features of their life otherwise incomprehensible. In the first place, it is evident that their activities center largely around the care for the young. The larva develops from the egg as a helpless, footless maggot, unable to forage for itself, unable to protect itself from enemies. It is dependent among bees and wasps upon the food supplies stored up in the cell with the egg. Among ants, it is fed directly by the workers by regurgitation from their crops. Solitary wasps form a group to be considered by themselves. Thus the digger wasp, or specks, does not live in communities, but the females make separate nests, one for each egg, provisioning them with insect prey which they sometimes kill, but more generally merely paralyze beforehand by stinging them. J. H. Fabra describes their habits in his insect life as follows. The nests may be of mud and attached for shelter under leaves, rocks, or eaves of buildings, or may be burrows hollowed out in the ground, in trees, or in the stems of plants. The adult wasp lives upon fruit or nectar, but the young grub or larva must have animal food, and here the parent wasp shows a rigid conservatism, each species providing the sort of food that has been approved by its family for generations, one taking flies, another bugs, and another beetles, caterpillars, grasshoppers, crickets, locusts, spiders, cockroaches, aphids, or other creatures, as the case may be. The solitary wasp mate soon after leaving the nest in the spring or summer. The males are irresponsible creatures, aiding little, if at all, in the care of the family. When the egg-laying time arrives, the female secures her prey, which she either kills or paralyzes, places it in the nest, lays the egg upon it, and then in most cases closes the hole and takes no further interest in it, going on to make new nests from day to day. In some genera, the female maintains a longer connection with her offspring, not bringing all the provisions at once but returning to feed the larva as it grows, and only leaving the nest permanently when the grub has spun its cocoon and become a pupa. The egg develops in from one to three days into a footless maggot-like creature which feeds upon the store provided for it, increasing rapidly in size and entering the pupal stage in from three days to two weeks. In the cocoon, it passes through its final metamorphosis. Emerging is a perfect insects, perhaps in two or three weeks, or in many cases, after the winter months have passed and summer has come again. Probably no solitary wasp lives through the winter, those that have come out in the spring or summer perishing in the autumn. The habit common to almost all of the solitary wasp, says Kellogg, of so stinging the prey caterpillars, spiders, beetles, flies, bugs, or whatever other insects are used to provision the nest, as not to kill but only to paralyze it, is perhaps the most amazing part of all the interesting behavior of all these wasps. The advantage is obvious. Killed, the prey would quickly decompose, and the hatching carnivorous wasp larva would have only a mass of, to it, inedible, decaying flesh, instead of the fresh, live animal substance it demands. But if stored unhurt, the prey would, if a cricket or spider or similarly active animal, quickly escape from the burrow. Or if a caterpillar or weak bug at least succeed, albeit unwittingly, in crushing the tender wasp egg, by griggling about in the underground prison cell. More than that, unhurt, some insects could not live without food the many days that are necessary for the development of the wasp larva, especially in the face of the frantic and exhausting efforts they would be impelled to in their attempts to escape. But paralyzed there is no exertion, metabolism is slight, and life without food is capable of being prolonged many days. The paralysis is due to the stinging by the wasp of one or more of the ganglia or nerve centers of the ventral nerve cord. The amazing expertness and accuracy displayed in plunging the sting into exactly those spots where injury will give rise to exactly that physiological phenomenon in the prey that will make it available for the special conditions attending the wasp larva's sustenance. This adroitness and the seeming knowledge of the structure and the physiology of the prey have led some entomologists to credit the solitary wasp with anthropomorphic qualities that are quite unwarranted. The whole behavior is probably explicable as a complex and advantageous reflex or instinct developed by selection. Similarly, the whole course of the nest building and provisioning is an elaborate performance wholly for the sake of the young, which the mother will likely never see. And these young in turn will, if females, do the same thing, perfectly and in essentially if not exactly the same manner, without ever previously seeing such remarkable processes performed. All these complex and altruistic habits have naturally led to much speculation concerning their origin and their relation to psychical conditions. Whether a consciousness of what is being done and an intelligence is brought to bear upon its doing, whether we may contribute to the wasp a psychical state with its attributes of cognizance, reason, and emotion, these are questions which are debated warmly. The consensus of opinion, however, is distinctly adverse to reading into the behavior of Amophila or any of its allies anthropomorphic attributes of reason, consciousness, or emotion. The fixity and inevitableness, which is preeminently characteristic of the behavior of the wasp, and the fact that each female is ab ovo, adequate to carry through the complex train of actions without teaching, experience, or opportunity for imitation, practically prove all this seeming marvel of reasoned care for the future young to be an inherited instinct incapable of essential modification except by the slow process of selection through successive generations. The social wasp, hornets, yellow jackets, and such, live in great communities of males, females, and a third caste, the neuters or workers. These last are in reality sterile females, taking no part in the reproduction of the race, but take charge of the building and caring for the nest of the community, bringing food and rearing the young. The life history of a community in general outline is given by Kellogg as follows. In the early spring, fertilized females, or queens, which have hibernated as adults in sheltered places as crevices in stone walls, under logs, stones, etc., come out from their winter hiding places and each makes a small nest containing a few brood cells. In each cell an egg is laid and food consisting of insects killed and somewhat masticated is hunted for and brought to the larvae throughout their brief life by the queen. The larvae soon pupate in the cells and in a few days issue as winged wasp. They are exclusively workers. These workers now enlarge the nest adding more brood cells in which the queen deposits eggs. The bringing of food and the care of the young now devolve on the workers. The new or second brood also is composed of workers only, and these immediately reinforce the first brood in the work of enlarging the nest and building new brood cells. Thus through the summer several broods of workers are reared until the late summer or early fall a brood containing males and females as well as workers appears. The community is now at its maximum both as regards population and size of nest. In the species Vespa, which make the great ball-like aerial nests, the community may grow to number several thousand individuals. The males and females mate, presumably with members of other communities, but no more eggs are laid and with the gradual coming on of winter the males and workers and many of the females die. There persist only as survivors of each community a few fertilized females. These crawl into safe places to pass the winter. Any social wasp found in wintertime is thus almost certainly a queen. Those of the queens which come safely through the long winter found the communities which lived through the following season. The social wasp of the genus Vespa the familiar yellow jackets and hornets are the ones which build the large sub-spherical nests familiar to all outdoor observers and related to much boyish adventure. Inside the great globe are several horizontal combs of brood cells and tears all enclosed by several layers of wasp paper. The large bald-faced hornet Vespa maculata is the best known builder of the globe nests. The smaller yellow jackets Vespa germanica Vespa cuneita build in hollows in stumps or stone fences or underground. Such protected or underground nests are not as thoroughly or thickly enveloped in paper as are the exposed arboreal globe nests. The miniature queen nest of the Vespa with the single little brood comb inside may often be found by careful searching in the spring. The long-bodied blackish wasp of the genus polystase build single exposed horizontal combs out of wasp paper or chewed wood which are attached to the underside of porch roofs eaves ceilings of outbuildings etc by a short central stem. The little comb made by the queen may contain but half a dozen cells but after the workers hatch many other cells are added around the margin. But the nest and workers never compare in size and numbers with the large communities of Vespa. Among all the wasps the adult feeds upon nectar of flowers but the larva is fed on insects paralyzed or freshly killed. The solitary kinds store up food and place it in the cell with the egg. The social wasp do not but the queen at first and afterward the workers forage for insects which they bring in constantly and feed to the larva in a killed and partially masticated condition. Bees differ from wasp in that the young larva as well as the adult is fed upon the nectar and pollen of flowers converted into honey and bee bread instead of upon insect food as in the wasp. The structure of the mouth parts and the instincts of the bee differ accordingly. There are a great many kinds of solitary bees but the social bees the wild bumble bee and the hive bee are by far the most familiar. In the solitary bees there are only males and females in the social bees as in social wasp there are males females and workers. The bumble bee's nest underground occupying and enlarging a mouse hole or small burrow and the life history of the community is much like that of the wasp. They do not make honey cells but mix pollen and honey to a pasty mass deposit a few eggs upon the mass and in the later stages of the nest build waxen cells for the larva to pupate in. The honey bees melapona and apis have a much more elaborated community life and unlike the wasp and bumble bees this does not terminate with the summer but is continuous from season to season. The melaponas are tropical bees stingless or nearly so living in immense communities whose life history is not completely known. The better known hive bees apis are native to the old world but domesticated and introduced everywhere. The habits and life history of the great hive bee communities have been more carefully studied than any other phase of insect life yet there are many unsolved problems especially in regard to the interpretation and meaning of their behavior. A well-written and reliable account of the life of the hive bees is given in Jordan and Kellogg's evolution and animal life from which the following may be quoted. An interesting series of gradations from a strictly solitary through a gregarious to an elaborately specialized communal life is shown by the bees. Although the bumble bee and the honey bee are so much more familiar to us than other bee kinds that the communal life exemplified by them may have come to seem the usual kind of bee life yet as a matter of fact there are many more solitary bees than social ones. The general character of the domestic economy of the solitary bees is well shown by the interesting little green carpenter bee Saratina dupla. Each female of this species bores out the pith from five or six inches of an elder branch or raspberry cane and divides this space into a few cells by means of transverse partitions. In each cell she lays an egg and puts within enough food flour pollen to last the grub or larvae through its life. She then waits in an upper cell of the nest until the young bees issue from their cells when she leads them off and each begins active life on its own account. The mining bees Andrina which make little burrows in a clay bank live in large colonies that is they make their nest burrows close together in the same clay bank but each female makes her own burrow lays her own eggs in it furnishes it with food a kind of paste of nectar and pollen and takes no further care of her young nor has she at any time any special and dressed in her neighbors but with the smaller mining bees belonging to the genus Helictus several females unite in making a common burrow after which each female makes side passages her own extending from the main or public entrance burrow as a well known entomologist has said Andrina builds villages composed of individual homes while Helictus makes cities composed of apartment houses the bumblebee however establishes a real community with a truly communal life although a very simple one the few bumblebees which we see in winter time are queens all others die in the autumn in the spring a queen selects some deserted nest of a field mouse or a hole in the ground gathers pollen which she molds into a rather large irregular mass and puts into the hole and lays a few eggs on the pollen mass the young grubs or larvae which soon hatch feed on the pollen grow pupate and issue as workers winged bees a little smaller than the queen these workers bring more pollen enlarge the nest and make irregular cells in the pollen mass in each of which the queen lays an egg she gathers no more pollen does no more work except that of egg laying from these new eggs are produced more workers and so on until the community may come to be large later in the summer males and females are produced and mate with the approach of winter all the workers and males die leaving only the fertilized females the queens to live through the winter and found new communities in the spring the social wasp as with the bees there are many more kinds of solitary wasp than social ones show a communal life like that of the bumblebees the only yellow jackets and hornets that live through the winter are fertilized females or queens when spring comes each queen builds a small nest suspended from a tree branch or in a hole in the ground which consists of a small comb enclosed in a covering or envelope open at the lower end the nest is composed of wasp paper made by chewing bits of weather beaten wood taken from all fences or outbuildings in each of the cells the queen lays an egg she deposits in the cell a small mass of food consisting of some chewed insects or spiders from these eggs hatch grubs which eat the food prepared for them grow pupae and issue as worker wasp winged and slightly smaller than the queen the workers enlarge the nest adding more combs and making many cells in each of which the queen lays an egg the workers provision the cell with chewed insects and other broods of workers are rapidly hatched the community grows in numbers and the nest grows in size until it comes to be the great ball-like oval mass which we know so well as a hornet's nest a thing to be left untouched when disturbed the wasp swarm out of the nest and fiercely attack any invading foe in sight after a number of broods of workers has been produced broods of males and females appear and mating takes place in the late fall the males and all of the many workers die leaving only the new queens to live through the winter end of section seven recording by melanie young section eight of the science history of the universe volume six this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org the science history of the universe volume six edited by frances rolt wheeler zoology chapter five insect social communities part two honeybees live together as we know in large communities we are accustomed to think of honeybees as the inhabitants of beehives but there were bees before there were hives the bee tree is familiar to many of us the bees in nature make their home in the hollow of some dead or decaying tree trunk and carry on there all the industries which characterize the busy communities in the hives a honeybee community comprises three kinds of individuals namely a fertile female or queen numerous males or drones and many infertile females or workers and many infertile females or workers these three kinds of individuals differ in external appearance sufficiently to be readily recognizable the workers are smaller than the queens and drones and the last two differ in the shape of the abdomen or hind body the abdomen of the queen being longer and more slender than that of the male or drone in a single community there is one queen a few hundred drones and 10 to 30 thousand workers the number of drones and workers varies at different times of the year being smallest in winter each kind of individual has certain work or business to do for the whole community the queen lays all the eggs from which newbies are born that is she is the mother of the entire community the drones or males have simply to act as royal consorts upon them depends the fertilization of the eggs the workers undertake all the food getting the care of the young bees the comb building the honey making all the industries with which we are more or less familiar that are carried on in the high and all the work done by the workers is strictly work for the whole community in no case does the worker be work for itself alone it works for itself only in so far as it is a member of the community how varied and elaborately perfected these industries are may be perceived from a brief account of the life history of a bee community the interior of the hollow in the beetry or of the hive is filled with comb that is with wax molded into hexagonal cells and supports for these cells the molding of these thousands of symmetrical cells is accomplished by the workers by means of their specially modified trowel like mandibles or jaws the wax itself of which the cells are made comes from the bodies of the workers in the form of small liquid drops which exude from the skin on the underside of the abdomen or hinder body rings these droplets run together harden and become flattened and are removed from the wax plates as the peculiarly modified parts of the skin which reduce the wax are called by means of the hind legs which are furnished with scissor like contrivances for cutting off the wax in certain of the cells are stored the pollen and honey which serve as food for the community the pollen is gathered by the workers from certain favorite flowers and is carried by them from the flowers to the hive in the pollen baskets the slightly concave outer surface of one of the segments of the broaden and flattened hind legs this concave surface is lined on each margin with a row of incurved stiff hairs which hold the pollen mass securely in place the honey is the nectar of flowers which has been sucked up by the workers by means of their elaborate lapping and sucking mouth parts and swallowed into a sort of honey sack or stomach then brought to the hives and regurgitated into the cells this nectar is at first too watery to be good honey so the bees have to evaporate some of this water many of the workers gather above the cells containing the nectar and buzz that is vibrate their wings violently this creates currents of air which pass over the exposed nectar and increase the evaporation of the water the violent buzzing raises the temperature of the bees bodies and this warmth given off to the air also helps make evaporation more rapid in addition to bringing in food the workers also bring in when necessary propolis or the resinous gum of certain trees which they use in repairing the hive as closing up cracks and crevices in it in many of the cells there will be found not pollen or honey but the eggs or the young bees in larval or pupil condition the queen moves about through the hive laying eggs she deposits only one egg in a cell in three days the egg hatches and the young bee appears as a helpless soft white footless grub or larvae it is cared for by certain of the workers that may be called nurses these nurses do not differ structurally from the other workers but they have the special duty of caring for the helpless young bees they do not go out for pollen or honey but stay in the hive they are usually the new bees i.e. the youngest or most recently added workers after they act as nurses for a week or so they take their places with the food gathering workers and other new bees act as nurses the nurses feed the young or larval bees at first with a highly nutritious food called bee jelly which the nurses make in their stomach and regurgitate for the larvae after the larvae are two or three days old they are fed with pollen and honey finally a small mass of food is put into the cell and the cell is capped or covered with wax each larvae after eating all its food in two or three days more changes into a pupa which lies chiescent without eating for 13 days when it changes into a full-grown bee the new bee breaks open the cap of the cell with its jaws and comes out into the hive ready to take up its share of the work for the community in a few cases however the life history is different the nurses will tear down several cells around some single one and enlarge this inner one into a great irregular vase-shaped cell when the egg hatches the grub or larva is fed bee jelly as long as it remains a larva never being given ordinary pollen and honey at all this larva finally pupates and their issues from the pupa not a worker or drone bee but a new queen bee the egg from which the queen is produced is the same as the other eggs but the worker nurses by feeding the larva only the highly nutritious bee jelly make it certain that the new bee shall become a queen instead of a worker it is also to be noted that the male bees or drones are hatched from eggs that are not fertilized the queen having an in her power to they either fertilized or unfertilized eggs from the fertilized eggs hatch larva which develop into queens or workers depending on the manner of their nourishment from the unfertilized eggs hatch the males when several queens appear there is much excitement in the community each community has normally a single one so that when additional queens appear some rearrangement is necessary the rearrangement comes about first by fighting among the queens until only one of the new queens is left alive then the old or mother queen issues from the hive or tree followed by many of the workers she and her followers fly away together finally alighting on some tree branch and massing there in a dense swarm this is the familiar phenomenon of swarming the swarm finally finds a new hollow tree or in the case of the hive bee the swarm is put into a new hive where the bees build cells gather food produce young and thus found a new community this swarming is simply an emigration which results in the wider distribution and in the increase of the number of the species it is a peculiar but effective mode of distributing and perpetuating the species the community it is important to note is a persistent or continuous one the workers do not live long the spring broods usually not over two or three months and the fall broods not more than six or eight months but new ones are hatching while the old ones are dying and the community as a whole always persists the queen may live several years perhaps as many as five she lays about one million eggs a year the ants may fairly be regarded as the highest group of invertebrate animals they excel in the variety and complexity of their instincts and the elaborateness of their social organization and their abundance and wide distribution marks them as one of the most successful and dominant types produced by evolution there are no solitary ants all of them have a highly complex social life live in large communities composed of males females and workers the workers sterile females are the principal part of an ant colony only at the mating season do males and females appear in any considerable numbers the workers are wingless and much smaller than the males and females the latter are winged only for the mating or swarming season when they leave the nest after mating the males die and the females or queens throwing off their wings proceed each to found a new colony aside from their mating flights ants are all strictly terrestrial their nests are a maze of underground galleries and chambers tunneled out by the workers and serving as a retreat for the adults a nursery for the young a granary for stored up food and in one group of ants as a vegetable garden as well the colony consists usually of a queen ant or in some instances several queens whose duties are confined to egg laying of a great number of workers of two or more casts worker minors worker majors and sometimes soldiers and at certain seasons of the winged males and females ready to issue from the nest mate and form new colonies the duties of the different cast of workers vary to the youngest and smallest ones are assigned to the care of the eggs and feeding of the larvae the larger workers forage for food while the soldiers large headed in with powerful jaws apparently do little besides protecting the nest in case of attack ants are primarily carnivorous they subsist on other insects or upon sweet juices exuding from flowers leaves or stems or secreted by insects they are extremely fond of the honeydew secreted by the plant lice or aphids which with many of the common species forms an important part of their food on every plant infested by aphids one is pretty certain to see a number of ants in attendance stimulating the excretion of the honeydew by deft stroking many are the stories that have been told of the curious relations between ant and aphis but many of them need to be verified by more careful investigation nevertheless it is certain that the ants do take care of their cows as lineas called them in a way that is at least suggestive of domestication if the various ants attending aphids on one plant are observed they will be found to be all of one species and apparently all from one nest one might assume from this but probably quite incorrectly that aphids were considered as personal or rather municipal property among the ants again certain ants build a sort of tent of mud or vegetable fiber over parts of branches or stems infested with aphids or scale insects and this tent serving to protect and shelter both the ants and their cows from rain or from incursions of enemies or other ants may fairly be regarded as a stable furthermore in at least one common species of ant the workers have been seen to take the newly hatched corn root aphids and carefully place them upon the roots of certain species of knotweed guard and protect them there until the corn roots were sufficiently advanced and then to remove the aphids to feed upon the corn there can be no question that the mere presence of such bold active and efficient fighters as the ants must serve to keep away enemies from the slow and helpless aphids but to what further extent the ants actively protect their charges is not so clear the most familiar traditional aspect of ant life the storing up of grain for a winter supply is illustrated in the is illustrated in the harvester or agricultural ants whose nests are conspicuous in open grassy places and especially in arid or nearly desert regions they bring into their nest great quantities of grain and grass seeds and have been even credited with deliberate planting for harvest of certain kinds of grass seed of which they are very fond this last however is discredited by wheeler the excitants or foraging ants are fierce predatory insects well known in west africa and tropical america they are nomadic having no fixed habitations but travel mostly by night in enormous armies which seek out and destroy every living animal in their path the approach of these great columns strikes terror and confusion into all the varied life of the tropical forests beast bird and man hasten to get out of their path dwellings are promptly vacated on notice of their appearance and they swarm through the house seek out every cranny and crevice attack and tear to pieces insects mice rats and vermin of every kind and retire loaded with booty to their nests which are mere temporary camps excavated between stones or other convenient shelter they are blind or nearly so and traveling chiefly by night are guarded by their antennae sense which as in most other ants practically takes the place of sight in higher animals travelers in the forest whose camps are in the line of march of an army of driver ants find themselves suddenly covered by swarms of big black insects biting fiercely at every unprotected spot and have to run for their lives abandoning camp baggage and clothing for a time to the mercies of their savage assailants their household visitations are regarded as a blessing for the dwelling is clear of vermin dead or alive when they get through with it and a temporary eviction as a small price for the owners to pay where vermin swarm as they do in the tropics these salbas or leaf cutting ants are among the most remarkable of all the social insects they are abundant in tropical america and species of this group are found as far north as new jersey in south and central america they build enormous nest with fast ramifications of galleries and passages which extend for many yards and are even said to tunnel under considerable rivers their curious habit of cutting out little pieces of leaves and carrying them to their nests was noticed by early explorers and is referred to even in some of the indian legends but it was long a mystery what they did with the leaves ants generally are dependent for food upon other insects animal matter or upon sweet juices which they obtain in various ways they do not usually eat ordinary vegetation and while the salbas might be supposed an exception to the rule there was no evidence that they ate the leaf fragments which they so carefully conveyed to their homes professor bates who saw their work on the amazon valley was of the opinion that they used the leaves to thatch their galleries and protect them from the heavy tropic rains the true explanation was suggested in 1874 by thomas belt the leaves are used as manure in which they grow and cultivate a peculiar species of fungus on which they feed within the nest several feet below the ground they excavate large cavities often a foot in diameter which are veritable underground gardens tended weeded and manned by different grades of workers the little leaf fragments are brought to these cavities cut crushed and manipulated into small round pellets and planted in the surface of the garden to serve as nutriment for the fungus to grow upon under the care of the ants the fungus is not allowed to produce spores but only to grow in thread-like filaments from which clusters of transparent globules bud off these latter forming the food of the ants all other kinds of fungus growth are carefully kept down and the temperature and moisture of the fungus garden is regulated by opening or closing the openings at the top of the nest which seem to be chiefly ventilation holes the ants issuing and returning by other openings more or less distant these insects observes wheeler in the fierce struggle for existence everywhere a parent in the tropics have developed a complex group of instinctive activities which enables them to draw upon an ever-present inexhaustible food supply through utilizing the foliage of plants as a substratum for the cultivation of edible fungi no wonder therefore that having emancipated themselves from the precarious diet of other ants which subsist on insects the sweet exudations of plants and excrement the atti have become the dominant invertebrates of tropical america the nest are guarded by large soldier workers with massive heads and powerful jaws smaller workers of several different sizes have assigned to them the various tasks of collecting leaves of excavating the tunnels and galleries of cultivating manuring and weeding the fungus and of feeding the young helpless larvae the nurse girls of the colony being the smallest and youngest of the workers upon leaving the nest for the foundation of a new colony the female carries with her a small pellet of the fungus which is carefully tended and manured until the new colony has become established these saba ants are not the only fungus growing insects among the termites which although not true ants resemble them in appearance and social habits there are certain kinds that also cultivate a species of fungus which they use for food the worker sex however is said to feed upon dead wood and to receive no share of the fungus which it spends so much time in cultivating among the wood boring beetles the ambrosia beetles also cultivate and feed upon certain kinds of fungus growing it on the walls of the galleries which they excavate the honey ants mermicocystis are a unique group these curious little ants store up honey like the bees but in a very different way instead of building cells of wax they store it up in the bodies of certain of the workers in which the abdomen becomes enormously distended so that they are veritable living cask these individuals do not leave the nests but are fed by the active workers and when replete hang from the roof of enlarged chambers in the runways in seasons of scarcity they are able in turn to feed the rest of the community by the same method of regurgitation they inhabit the arid southwestern united states and were studied and described by professor mccook from the garden of the gods in colorado leading a rather precarious existence in a region where food is abundant only for a short season in the year the advantage of this habit can readily be seen and there are certain advantages about living cask and being more readily removed from danger than the fixed storehouses of the bees a curious development of the social life of ants is seen in the so-called slave making ants two of these the sanguinary ant or red slave maker for mica sanguania and the amazon ant polyurgis are well known and their habits have been carefully studied the most recent studies and interpretation being by wheeler the sanguinary ant makes raids upon the nests of other ants but in particular upon the smaller brown species for mica fusca killing the workers carrying off eggs and larvae to its own nest most of the larvae are used for food but a part of them are reared and brought up in the nest of their captors they become loyal members of the new community and take part in the multifarious activities of the nest going out in search of food carrying for the eggs feeding the larvae excavating or extending the nest and so on it does not appear that they take part in the raids on other ant nests but probably this is merely because such raids are conducted by the larger and more powerful workers only in any ant community the resemblance here to slave making in the human race is more superficial than real worker ants are never captured in these raids and the larvae reared in the nest of the captors are not an unwilling and inferior race forcibly held in subjection and treated as an inferior cast the nest is rather to be considered as a mixed community in which the division of labor is based on the capabilities of the individual but not on his race nevertheless if it is considered that it is only the worker larvae of the smaller species that are reared and that they help to rear and care for the young of an alien race instead of their own this slave making does involve the exploiting of the weaker for the benefit of the more powerful race in the amazon ant a further development of the slave making instinct appears which may serve to show where the weak point lies in this method of exploitation in this species the workers have become largely dependent upon the captured race not only for the care of the nest and rearing of the young but for food as well so that they are unable to feed or groom themselves under these conditions the continuance of the amazon ant communities obviously becomes dependent upon the prosperity and abundance of colonies of the smaller species the slave making race cannot prosper at the expense of the other beyond a certain limit and its relations tend to become analogous to those of parasitic animals in several kinds of ants the female instead of depending upon her own progeny to start a new colony may seek out a small existing colony of her own or some other species and persuade or compel the workers to adopt her this process has been carefully observed by wheeler and distinguished from the slave making habits with which it might readily be confused both result in mixed communities in which the larger species is more or less dependent upon the smaller in its household and personal activities but the slave making results from the carrying off of larvae from raided nests the social parasitism from the adoption by an ant community of a queen of alien race it is not wholly clear in spite of the careful observations of wheeler and others how the invading queen manages to overcome the strong instinct of antagonism and the workers to an ant of another community or race but this parasitism is carried in some species so far that the invading race has no workers only males and females and is wholly dependent upon its host for sustenance there is a great variety of parasitism social and individual to be seen in ant communities and the careful study of its nature has thrown much light on the nature and limits of the intelligence of these insects there are several kinds of smaller ants that live in mixed communities with larger forms but construct separate galleries opening into the larger galleries of their host but too small for the larger ants to traverse among these some like the thief ant solenopsis prey upon the larvae and pupa of the larger form while others merely levy toll upon the supplies brought in by the larger workers again there are various insects of other orders flies bugs and spiders which make their homes in ant nests some are harmless or even beneficial in the life of the community but others are ravenous and destructive enemies of the ants preying upon the eggs or larva laying their own eggs within the ant larvae to develop at their expense and in various ways seriously interfering with the prosperity of the nest yet the eggs and larvae of these parasites are as carefully tended and reared by the ants as their own and the adults are evidently tolerated by the workers either because they are unobserved or because they are regarded as nest mates or for some other reason still obscure end of section eight recording by melanie young