Chapter II: Anatomy and Physiology (1)

In this chapter I shall give first the general anatomy of insects; then the anatomy, and still more wonderful physiology of the honey-bee.

ANATOMY OF INSECTS.

In all insects the body is divided into three well-marked portions (Fig. 2): the head (Figs. 4 and 5), which contains the mouth-organs, the eyes, both the compound and when present the simple, and the antennæ; the thorax, which is composed of three rings, and gives support to the one or two pairs of wings, and to the three pairs of legs; and the abdomen, which is composed of a variable number of rings, and gives support to the external sex-organs, and when present to the sting. Within the thorax there are little more than muscles, as the concentrated strength of insects, which enables them to fly with such rapidity, dwells in this confined space. Within the abdomen, on the other hand, are the sex-organs, by far the greater and more important portions of the alimentary canal, and other important organs.

ORGANS OF THE HEAD.

Of these the mouth organs (Fig. 6) are most prominent. These consist of an upper lip--labrum--and under lip--labium--and two pairs of jaws which move sidewise; the stronger, horny jaws, called mandibles, and the more membranous, but usually longer, maxillæ. The labrum (Fig. 6, _l_) is well described in the name upper lip. It is attached, usually, by a movable joint to a similarly shaped piece above it, called clypeus (Fig. 6, _c_), and this latter to the broad epicranium (Fig. 6, _o_), which contains the antennæ, the compound, and, when present, the simple eyes.

The labium (Fig. 15) is not described by the name under lip, as its base forms the floor of the mouth, and its tip the tongue. The base is usually broad, and is called the mentum, and from this extends the tongue (Fig. 15, _a_) or ligula. On either side, near the junction of the ligula and mentum, arises a jointed organ rarely absent, called the labial palpus (Fig. 6, _k k_), or, together, the labial palpi. Just within the angle formed by these latter and the ligula arise the paraglossæ (Fig. 15, _d_), one on either side. These are often wanting.

Head of Bee much magnified.

_o_--Epicranium
_e e_--Compound eyes.
_a a_--Antennæ,
_c_--Clypeus.
_l_--Labrum.
_m_--Jaws.
_m x_--2d Jaws.
_k k_--Labial palpi,
_t_--Ligula.
]

The jaws or mandibles (Fig. 6, _m, m_) arise one on either side just below and at the side of the labrum, or upper lip. These work sidewise instead of up and down as in higher animals, are frequently very hard and sharp, and sometimes armed with one or more teeth. A rudimentary tooth (Fig. 21, _b_) is visible on the jaws of drone and queen bees.

Beneath the jaws or mandibles, and inserted a little farther back, are the second jaws or maxillæ (Fig. 6, _m x_), less dense and firm than the mandibles, but far more complex. They arise by a small joint, the cardo, next this is a larger joint, the stipes, from this extends on the inside the broad lacinia (Fig. 20, _c_) or blade, usually fringed with hairs on its inner edge, towards the mouth; while on the outside of the stipes are inserted the--from one to several jointed--maxillary palpi. In bees these are very small, and consist of two joints, and in some insects are wholly wanting. Sometimes, as in some of the beetles, there is a third member running from the stipes between the palpus and lacinia called the galea. The maxillæ also move sidewise, and probably aid in holding and turning the food while it is crushed by the harder jaws, though in some cases they, too, aid in triturating the food.

These mouth parts are very variable in form in different insects. In butterflies and moths, two-wing flies and bugs, they are transformed into a tube, which in the last two groups forms a hard, strong beak or piercer, well exemplified in the mosquito and bed-bug. In all the other insects we find them much as in the bees, with the separate parts varying greatly in form, to agree with the habits and character of their possessors. No wonder DeGeer and Fabricius detected these varying forms as strongly indicative of the nature of the insect, and no wonder, too, that in their use they were so successful in forming a natural classification.

Every apiarist will receive great benefit by dissecting these parts and studying their form and relations for himself. By getting his children interested in the same, he will have conferred upon them one of the rarest of blessings.

To dissect these parts, first remove the head and carefully pin it to a cork, passing the pin through, well back between the eyes. Now separate the parts by two needle points, made by inserting a needle for half its length into a pine stick the shape of a pipe-stem, leaving the point projecting for an inch or more. With one of these in each hand commence operations. The head may be either side up. Much may be learned in dissecting large insects, even with no glass; but in all cases, and especially in small insects, a good lens will be of great value. The best lens is one of Tolles', sold by Mr. Stoddard, of the Boston optical works. These are very excellent and thus high priced, costing $14.00. Gray's triplet hand-lenses are very good, are cheap, and can be procured for about $2.00 of any optician. The handle should have a hole through it to permit of mounting it above the object, so that it will hold itself. Tolles' lenses are easily mounted, in a stand which any one can contrive and make in twenty minutes. I value my Tolles' lens even more highly than my large compound microscope, which cost $150. Were I obliged to part with either, the latter would go.

I require my students to do a great deal of dissecting, which they enjoy very much and find very valuable. I would much rather that my boy would become interested in such study, than to have him possessor of infinite gold rings, or even a huge gold watch, with a tremendous charm. Let such pleasing recreation gain the attention of our boys, and they will ever contribute to our delight, and not sadden us with anxiety and fear.

The antennæ (Fig. 6, _a, a_) are the horn-like jointed organs situated between or below and in front of the large compound eyes of all insects. They are sometimes short, as in the house-fly, and sometimes very long, as in the grasshoppers. They are either straight, curved or elbowed (Fig. 6). In form, too, they are very various, as thread-like, tapering, toothed, knobbed, fringed, feathered, etc. It is known that a nerve passes into the antennæ, but their exact function is little understood. That they serve as most delicate touch organs no apiarist can doubt. That they serve as organs of smell or hearing is not proved. That insects are conscious of sounds I think no observing person can doubt. It is proved by the call of the katy-did, the cicada and the cricket. What apiarist, too, has not noticed the effect of various sounds made by the bees upon their comrades of the hive. How contagious the sharp note of anger, the low hum of fear, and the pleasant tone of a new swarm as they commence to enter their new home. Now, whether insects take note of these vibrations, as we recognize pitch, or whether they just distinguish the tremor, I think no one knows. There is some reason to believe that their delicate touch-organs may enable them to discriminate between vibrations, even more acutely, than can we by use of our ears. A slight jar will quickly awaken a colony of hybrids, while a loud noise will pass unnoticed. If insects can appreciate with great delicacy the different vibratory conditions of the air by an excessive development of the sense of touch, then undoubtedly the antennæ may be great aids. Dr. Clemens thought that insects could only detect atmospheric vibrations. So, too, thought Linnæus and Bonnet. Siebold thinks, as the antennæ receive but one nerve, and are plainly touch-organs, they cannot be organs of hearing. Kirby has noticed that some moths turn their antennæ towards the direction from which noise proceeds, and thus argues that antennæ are organs of hearing. Grote, for a similar reason, thinks that the densely feathered antennæ of the males of various night moths, serve both for smell and hearing. Prof. A. M. Mayer and Mr. C. Johnson (see American Naturalist, vol. 8, p. 574) have by various ingenious experiments, proved conclusively, that the delicate, beautifully feathered antennæ of the male mosquito are organs of hearing.

That insects have a very refined sense of smell is beyond question. How quickly the carrion-fly finds the carcass, the scavenger the filth, and the bee the precious nectar.

I have reared female moths in my study, and have been greatly surprised on the day of their leaving their cocoons, to find my room swarming with males. These bridegrooms entered an open window in the second-story of a brick building. How delicate must have been the sense by which they were led to make the visit, and thus made to grace my cabinet. Bees, too, have been known to dash against a shutter behind which were flowers, thus showing the superiority of their perception of odors, as also their poor vision. But odors are carried by the air, and must reach the insect through this medium. Is it not probable, that the various breathing mouths of insects are also so many noses, and that their delicate lining membranes abounding with, nerve filaments, are the great odor sentinels? This view was maintained by both Lehman and Cuvier, and explains this delicate perception of scents, as the breathing mouths are large and numerous, and most so in insects like bees and moths, which are most sensitive to odors. How quickly the bees notice the scent of a strange bee or queen, or the peculiar odor of the venom. I have known a bee to sting a glove, and in a trice the glove would be as a pin-cushion, with stings in lieu of pins. Sometimes the bees will dart for many feet, guided by this odor. Yet the odor is very pungent, as I have frequently smelt the poison before I felt the sting. I have tried the experiments of Huber and Lubbock, and know that such insects as bees and ants will take no note of food after the loss of their antennæ. But we must remember that this is a capital operation. With loss of antennæ, insects lose control of their motions, and in many ways show great disturbance. Is it not probable then that removing the antennæ destroys the desire for food, as does amputation with ourselves? Kirby believes with Huber, that there is a scent organ. Huber's experiments on which he based this opinion are, as usual, very interesting. He presented a coarse hair dipped in oil of turpentine--a substance very repugnant to bees--to various parts of a bee engrossed in sipping honey. The bee made no objection, even though it touched the ligula, until it approached the mouth above the mentum, when she became much disturbed. He also filled a bee's mouth with paste, which soon hardened, after which the bee paid no heed to honey placed near it. This was not so conclusive, as the bee may have been so disturbed as to lose its appetite. I have experimented a good deal, and am inclined to the following opinion: The antennæ are very delicate touch-organs or feelers, and are so important in their function and connection that removal produces a severe shock, but further we know but little about their function, if they have other, and from the very nature of the problem we will find it very difficult of solution.

The eyes are of two kinds, the compound, which are always present in mature insects, and the ocelli or simple eyes, which may or may not be present. When present there are usually three, which if we join by lines, we will describe a triangle, in the vertices of whose angles are the ocelli. Rarely there are but two ocelli, and very rarely but one.

The simple eyes (Fig. 4, _f f f_) are circular, and possess a cornea, lens and retina, which receives the nerve of sight.

From the experiments of Réaumur and Swammerdam, which consisted in covering the eyes with varnish, they concluded that vision with these simple eyes is very indistinct, though by them the insect can distinguish light. Some have thought that these simple eyes were for vision at slight distances. Larvæ, like spiders and myriapods, have only simple eyes.

The compound eyes (Fig. 2, _e_) are simply a cluster of simple eyes, are situated one on either side of the head, and vary much in form and size. Between or below these are inserted the antennæ. Sometimes these last are inserted in a notch of the eyes, and in a few cases actually divide each eye into two eyes.

The eyes may meet above as in drones (Fig. 4), most two-wing flies and dragon-flies, or they may be considerably separated, as in the worker-bees (Fig. 5). The separate facets or simple eyes, of each compound eye, are hexagonal, or six-sided, and in the microscope look not unlike a section of honey-comb. The number of these is prodigious--Leeuwenhoek actually counted 12,000 in the eye of a dragon-fly--while some butterflies have, over 17,000. The compound eyes are motionless, but from their size and sub-spherical shape, they give quite a range of vision. It is not likely that they are capable of adjustment to accord with different distances, and it has been supposed, from the direct darting flight of bees to their hives, and the awkward work they make in finding a hive when moved only for a short distance, that their eyes are best suited to long vision.

Sir John Lubbock has proved, by some interesting experiments with strips of colored paper, that bees can distinguish colors. Honey was placed on a blue strip, beside several others of various colors. In the absence of the bees he changed the position of this strip, and upon their return the bees went to the blue strip rather than to the old position. Our practical apiarists have long been aware of this fact, and have conformed their practice to the knowledge, in giving a variety of colors to their hives. Apiarists have frequently noted that bees have a rare faculty of marking positions, but, for slight distances, their sense of color will correct mistakes which would occur if position alone was guide.

APPENDAGES OF THE THORAX.

The organs of flight are the most noticeable appendages of the thorax. The wings are usually four, though the Diptera have but two, and some insects--as the worker ants--have none. The front or primary wings (Fig. 3, _A_) are usually larger than the secondary or hind wings (Fig. 3, _B_), and thus the mesathoracic or middle ring of the thorax, to which they are attached, is usually larger than the metathorax or third ring. The wings consist of a broad frame-work of veins (Fig. 3), covered by a thin, tough membrane. The main ribs or veins are variable in number, while towards the extremity of the wing are more or less cross-veins, dividing this portion of the wings into more or less cells. In the higher groups these cells are few, and quite important in classifying. Especially useful are the cells in the second row, from the frontal or costal edge of the front wings, called the sub-costal cells. Thus in the genus Apis there are three such cells (Fig. 3, _A_, 1, 2, 3), while in the Melipona there are only two. The ribs or veins consist of a tube within a tube. The inner one forming an air tube, the outer one carrying blood. On the costal edge of the secondary wings we often find hooks, to attach it to the front wings (Fig. 3, _B_, _a_).

_Thorax of Bee magnified three times._

_a, a, a_--Muscles. _b, b_--Crust.]

The wings are moved by powerful muscles, compactly located in the thorax (Fig. 7, _a, a, a_), whose strength, as well as the rapidity of the vibrations of the wings when flight is rapid are really beyond computation. Think of a tiny fly outstripping the fleetest horse in the chase, and then marvel at this wondrous mechanism.

The legs (Fig. 2, _g, g, g_) are six in number in all mature insects, two on the lower side of each ring of the thorax. These are long or short, weak or strong, according to the habit of the insect. Each leg consists of the following joints or parts: The coxæ (Fig. 24), which move like a ball and socket joint in the close-fitting coxal cavities of the body-rings. Next to these follow in order the broad tracanter, the large, broad femur (Fig. 2, _g′_, 1), the long, slim tibia (Fig. 2, _g′_, 2), frequently bearing strong spines at or near its end, called tibial spurs, and followed by the from one to five-jointed tarsi (Fig. 2, _g′_, 3, 3, 3, 3, 3). All these parts move freely upon each other, and will vary in form to agree with their use. At the end of the last tarsal joint are two hooked claws (Fig. 2, _g′_, 4), between which are the pulvilli, which are not air-pumps as usually described, but rather glands, which secrete a sticky substance which enables insects to stick to a smooth wall, even though it be above them. The legs, in fact the whole crust, is more or less dense and hard, owing to the deposit within the structure of a hard substance known as chitine.

INTERNAL ANATOMY OF INSECTS.

The muscles of insects are usually whitish. Sometimes I have noticed quite a pinkish hue about the muscles of the thorax. They vary in form and position to accord with their use. The mechanism of contraction is the same as in higher animals. The ultimate fibers of the voluntary muscles, when highly magnified, show the striæ or cross-lines the same as do the voluntary muscles of vertebrates, and are very beautiful as microscopic objects. The separate muscles are not bound together by a membrane as in higher animals. In insects the muscles are widely distributed, though, as we should expect, they are concentrated in the thorax and head. In insects of swiftest flight, like the bee, the thorax (Fig. 7, _a, a, a_) is almost entirely composed of muscles; the œsophagus, which carries the food to the stomach, being very small. At the base of the jaws, too, the muscles are large and firm. The number of muscles is astounding. Lyonnet counted over 3,000 in a single caterpillar, nearly eight times as many as are found in the human body. The strength, too, of insects is prodigious. There must be quality in muscles, for muscles as large as those of the elephant, and as strong as those of the flea, would not need the fulcrum which the old philosopher demanded, in order to move the world. Fleas have been made to draw miniature cannon, chains, and even wagons many hundred times heavier than themselves.

The nerves of insects are in no wise peculiar so far as known, except in position. As in our bodies, some are knotted or have ganglia, and some are not.

The main nervous cord runs along the under or ventral side of the body (Fig. 8), separates near the head, and after passing around the œsophagus, enlarges to form the largest of the ganglia, which serves as a brain. The minute nerves extend everywhere, and in squeezing out the viscera of an insect are easily visible.

The organs of circulation in insects are quite insignificant. The heart is a long tube situated along the back, and receives the blood at valvular openings along its sides which only permit the fluid to pass in, when by contraction it is forced towards the head and emptied into the general cavity. Thus the heart only serves to keep the blood in motion. According to the best authorities, there are no special vessels to carry the blood to various organs. Nor are they necessary, as this nutritive fluid everywhere bathes the alimentary canal, and thus easily receives nutriment, or gives waste by osmosis, everywhere surrounds the tracheæ or air-tubes--the insect's lungs--and thus receives that most needful of all food, oxygen, and gives the baneful carbonic acid, everywhere touches the various organs, and gives and takes as the vital operations of the animal require.

The blood is light colored, and almost destitute of discs or corpuscles, which are so numerous in the blood of higher animals, and which give our blood its red color. The function of these discs is to carry oxygen, and as oxygen is carried everywhere through the body by the ubiquitous air-tubes of insects, we see the discs are not needed. Except these semi-fluid discs, which are real organs, and nourished as are other organs, the blood of higher animals is entirely fluid, in all normal conditions, and contains not the organs themselves or any part of them, but only the elements, which are absorbed by the tissue and converted into the organs, or, to be scientific, are assimilated. As the blood of insects is nearly destitute of these discs, it is almost wholly fluid, and is almost wholly made up of nutritious substance.

_Nervous System of the Drone magnified four times._]

The respiratory or breathing system of insects has already been referred to. Along the sides of the body are the spiracles or breathing mouths, which vary in number. These are armed with a complex valvular arrangement which excludes dust or other noxious particles. These spiracles are lined with a delicate membrane which abounds with nerves, which were referred to in speaking of them as smelling organs. From these extend the labyrinth of air-tubes (Fig. 2, _f, f′_), which breathe vitalizing oxygen into every part of the insect organism. In the more active insects--as in bees--the main tracheæ, one on each side of the abdomen, are expanded into large air-sacks (Fig. 2, _f_). Insects often show a respiratory motion, which in bees is often very marked. Newport has shown that in bees the rapidity of the respiration gauges the heat in the hive, and thus we see why bees, in times of severe cold, which they essay to keep at bay by forced respiration, consume much food, exhale much foul air and moisture, and are liable to disease. Newport found that in cases of severe cold there would be quite a rise of mercury in a thermometer which he suspended in the hive amidst the cluster. In the larva state, many insects breathe by fringe-like gills. The larval mosquito has gills in form of hairy tufts, while in the larval dragon-fly the gills are inside the rectum, or last part of the intestine. This insect, by a muscular effort, draws the water slowly in at the anus, when it bathes these singularly-placed branchiæ, and then makes it serve a further turn by forcibly expelling it, when the insect is sent darting ahead. Thus this curious apparatus not only furnishes oxygen, but also a mode of motion. In the pupa; of insects there is little or no motion, yet important organic changes are taking place--the worm-like, ignoble, creeping, often repulsive larva, is soon to appear as the airy, beautiful, active, almost ethereal imago. So oxygen, the most essential--the _sine qua non_--of all animal food, is still needed. The bees are too wise to seal the brood-cell with impervious wax, but rather add the porous capping, made of wax and pollen. The pupæ no less than the larvæ of some two-wing flies, which live in water, have long tubes which reach far out for the vivifying air, and are thus called rat-tailed. Even the pupæ of the mosquito, awaiting in its liquid home the glad time when it shall unfold its tiny wings and pipe its war-note, has a similar arrangement to secure the gaseous pabulum.

The digestive apparatus of insects is very interesting, and, as in our own class of animals, varies very much in length and complexity, as the hosts of insects vary in their habits. As in mammals and birds, the length, with some striking exceptions, varies with the food. Carnivorous or flesh-eating insects have a short alimentary canal, while in those that feed on vegetable food it is much longer.

_Alimentary Canal._

_o_--Honey stomach. _b_--True stomach.
_c_--Urinary tubes. _d_--Intestine.
]

The mouth I have already described. Following this is the throat or pharynx, then the œsophagus or gullet, which may expand, as in the bee, to form a honey or sucking stomach (Fig. 9, _o_), may have an attached crop like the chicken, or may run as a uniform tube as in our bodies, to the true stomach (Fig. 9, _b_). Following this is the intestine--separated by some into an ileum and a rectum--which ends in a vent or anus. In the mouth are salivary glands, which in larvæ that form cocoons are the source of silk. In the glands this is a viscid fluid, but as it leaves the duct it changes instantly into the gossamer thread. Bees and wasps use this saliva in building their structures. With it and mud some wasps make mortar; with it and wood, others their paper cells with it and wax, the bee fashions the ribbons that are to form the beautiful comb.

Lining the entire alimentary canal are mucous glands which secrete a viscid fluid that keeps the tube soft, and promotes the passage of food.

The true stomach (Fig. 9, _b_) is very muscular, and often a gizzard, as in the crickets, where its interior is lined with teeth. The interior of the stomach is glandular, for secreting the gastric juice which is to liquify the food, that it may be absorbed, or pass through the walls of the canal into the blood. Attached to the lower portion of the stomach are numerous urinary tubes (Fig. 9, _c_) though Cuvier, and even Kirby, call these bile tubes. Siebold thinks some of the mucous glands secrete bile, and others act as a pancreas.

The intestine when short, as in larvæ and most carnivora, is straight and but little if any longer than the abdomen, while in most plant eaters it is long and thus zig-zag in its course. Strange as it may seem, the fecal pellets of some insects are beautiful in form, and of others pleasant to the taste. In some caterpillars they are barrel-shaped, artistically fluted, of brilliant hue, and if fossilized, would be greatly admired, as have been the coprolites--fossil feces of quadrupeds--if set as gems in jewelry. As it is, they would form no mean parlor ornament. In other insects, as the Aphides or plant-lice, the excrement, as well as the fluid that escapes in some species from special tubes called the nectaries, is very sweet, and in absence of floral nectar, will often be appropriated by bees and conveyed to the hives. Imagination would make this a bitter draught, so here, as elsewhere in life, the bitter and sweet are mingled. In those insects that suck their food, as bees, butterflies, moths, two-wing flies and bugs, the feces are watery or liquid, while in case of solid food the excrement is solid.

SECRETORY ORGANS OF INSECTS.

I have already spoken of the salivary glands, which Kirby gives as distinct from the true silk-secreting tubes, though Newport gives them as one and the same. . In many insects these seem absent. I have also spoken of the mucous glands, the urinary tubules, etc. Besides these, there are other secretions which serve for purposes of defense: In the queen and workers of bees, and in ants and wasps, the poison intruded with the sting is an example. This is secreted by glands at the posterior of the abdomen, stored in sacks (Fig. 25, _c_), and extruded through the sting, as occasion requires. I know of no insects that poison while they bite, except it be mosquitoes, gnats, etc., and in these cases no special secreting organ has been discovered. Perhaps the beak itself secretes an irritating substance. A few exceedingly beautiful caterpillars are covered with branching spines, which sting about like a nettle. We have two such species. They are green, and of rare attraction, so that to capture them is worth the slight inconvenience arising from their irritating punctures. Some insects, like bugs, secrete a disgusting fluid or gas which affords protection, as by its stench it renders these filthy bugs so offensive that even a hungry bird or half-famished insect passes them by on the other side. Some insects secrete a gas which is stored in a sack at the posterior end of the body, and shot forth with an explosion in case that danger threatens thus by noise and smoke it startles its enemy, which beats a retreat. I have heard the little bombardier beetle at such times, even at considerable distances. The frightful reports about the terrible horn of the tomato-worm larva are mere nonsense. A more harmless animal does not exist. My little boy of four years, and girl of only two, used to bring them to me last summer, and fondle them as admiringly as would their father upon receiving them from the delighted children.

If we except bees and wasps, there are no true insects that need be feared; nor need we except them, for with fair usage even they, are seldom provoked to use their cruel weapon.

SEX ORGANS OF INSECTS.

The male organs consist first of the testes (Fig. 10, a) which are double organs. There may be from one, as in the drone bee, to several, as in some beetles, on each side the abdominal cavity. In these vesicles grow the sperm cells or spermatozoa, which, when liberated, pass through a long convoluted tube, the vas-deferens (Fig. 10, _b, b_), into the seminal sack (Fig. 10, c, c), where, in connection with mucous, they are stored. In most insects there are glandular sacks (Fig. 10, d) joined to these seminal receptacles, which in the male bee or drone are very large. The sperm cells mingled with these viscid secretions, as they appear in the seminal receptacle, ready for use, form the seminal fluid. Extending from these seminal receptacles is the ejaculatory duct (Fig. 10, _e, f, g_), which in copulation carries the male fluid to the penis (Fig. 10, _d_), through which it passes to the spermatheca of the female. Beside this latter organ are the sheath, the claspers when present, and in the male bee those large yellow sacks (Fig. 10, _i_), which are often seen to dart forth as the drone is held in the warm hand.

_Male Organs of Drone, much magnified._

_a_--Testes. _e_--Common duct.
_b, b_--Vasa deferentia. _f, g_--Ejaculatory sack.
_c, c_--Seminal sacks. _h_--Penis.
_d_--Glandular sacks. _i_--Yellow saccules.
]

_Queen Organs, greatly magnified._

_a, a_--Ovaries. _d_--Sting.
_b_--Oviducts. _e_--Spermatheca.
_c_--Oviduct.
]

The female organs (Fig. 11) consist of the ovaries (Fig. 11, _a, a_), which are situated one on either side of the abdominal cavity. From these extend the two oviducts, (Fig. 11, _b_), which unite into the common oviduct (Fig. 11, _c_) through which the eggs pass in deposition. In many insects there is beside this oviduct, and connected with it, a sack (Fig. 11, _e_) called the spermatheca, which receives the male fluid in copulation, and which, by extruding its contents, must ever after do the work of impregnation.

This sack was discovered and its use suggested by Malpighi as early as 1686, but its function was not fully demonstrated till 1792, when the great anatomist, John Hunter, showed that in copulation this was filled. The ovaries are multitubular organs. In some insects there are but very few tubes--two or three; while in the queen bee there are more than one hundred. In these tubes the ova or eggs _grow_, as do the sperm cells in the vesicles of the testes. The number of eggs is variable. Some insects, as the mud-wasps, produce very few, while the queen white-ant extrudes millions. The end of the oviduct, called the ovipositor, is wonderful in its variations. Sometimes it consists of concentric rings, like a spy-glass which may be pushed out or drawn in; sometimes of a long tube armed with augers or saws of wonderful finish, to prepare for eggs; or again of a tube which may also serve as a sting.

Most authors state that insects copulate only once, or at least that the female only meets the male but once. My pupil, Clement S. Strang, who made a special study of the structure and habits of bugs during the past season, noticed that the squash-bugs mated many times. It would be interesting to know whether these females possessed the spermatheca. In some cases, as we shall see in the sequel, the male is killed by the copulatory act. I think this curious fatality is limited to few species.

To study viscera, which of course requires very careful dissection, we need more apparatus than has been yet described. Here a good lens is indispensable. A small dissecting knife, a delicate pair of forceps, and some small, sharp-pointed dissecting scissors--those of the renowned Swammerdam were so fine at the point that it required a lens to sharpen them--which may also serve to clip the wings of queens--are requisite to satisfactory work. Specimens put in alcohol will be improved, as the oil will be dissolved out and the muscle hardened. Placing them in hot water will do nearly as well, in which case oil of turpentine will dissolve off the fat. This may be applied with a camel's-hair brush. By dissecting under water the loose portions will float off, and render effective work more easy. Swammerdam, who had that most valuable requisite to a naturalist, unlimited patience, not only dissected out the parts, but with small glass tubes, fine as a hair, he injected the various tubes as the alimentary canal and air-tubes. My reader, why may not you look in upon those wondrous beauties and marvels of God's own handiwork--nature's grand exposition? Father, why would not a set of dissecting instruments be a most suitable gift to your son? You might thus sow the seed which would germinate into a Swammerdam, and that on your own hearth-stone. Messrs. Editors, why do not you, among your apiarian supplies, keep boxes of these instruments, and thus aid to light the torch of genius and hasten apiarian research?

TRANSFORMATIONS OF INSECTS.

What in all the realm of nature is so worthy to awaken delight and admiration as the astonishing changes which insects undergo? Just think of the sluggish, repulsive caterpillar, dragging its heavy form over clod or bush, or mining in dirt and filth, changed, by the wand of nature's great magician, first into the motionless chrysalis, decked with green and gold, and beautiful as the gem that glitters on the finger of beauty, then bursting forth as the graceful, gorgeous butterfly; which, by its brilliant tints and elegant poise, out-rivals even the birds among the life-jewels of nature, and is made fit to revel in all her decorative wealth. The little fly, too, with wings dyed in rainbow-hues, flitting like, a fairy from leaf to flower, was but yesterday the repulsive maggot, reveling in the veriest filth of decaying nature. The grub to-day drags its slimy shape through the slums of earth, on which it fattens; to-morrow it will glitter as the brilliant setting in the bracelets and ear-drops of the gay and thoughtless belle.

There are four separate stages in the development of insects: The egg state, the larva, the pupa, and the imago.

THE EGG.

This is not unlike the same in higher animals. It has its yolk and its surrounding white or albumen, like the eggs of all mammals, and farther, the delicate shell, which is familiar in the eggs of birds and reptiles. Eggs of insects are often beautiful in form and color, and not infrequently ribbed and fluted as by a master-hand. The form of eggs is very various--spherical, oval, cylindrical, oblong, straight and curved (Fig. 26, _b_). All insects seem to be guided by a wonderful knowledge, or instinct, or intelligence, in the placing of eggs on or near the peculiar food of the larva. Even though in many cases such food is no part of the aliment of the imago insect. The fly has the refined habits of the epicure, from whose cup it daintily sips, yet its eggs are placed in the horse-droppings of stable and pasture.

Inside the egg wonderful changes soon commence, and their consummation is a tiny larva. Somewhat similar changes can be easily and most profitably studied by breaking and examining a hen's egg each successive day of incubation. As with the egg of our own species and of all higher animals, so, too, the egg of insects, or the yolk, the essential part--the white is only food, so to speak--soon segments or divides into a great many cells, these soon unite into a membrane--the blastoderm--and this is the initial animal. This blastoderm soon forms a single sack, and not a double sack, one above the other, as in our own vertebrate branch. This sack, looking like a miniature bag of grain, grows, by absorption, becomes articulated, and by budding out is soon provided with the various members. As in higher animals, these changes are consequent upon heat, and usually, not always, upon the incorporations within the eggs of the germ cells from the male, which enter the eggs at openings called micropyles. The time it takes the embryo inside the egg to develop is gauged by heat, and will, therefore, vary with the season and temperature, though in different species it varies from days to months. The number of eggs, too, which an insect may produce, is subject to wide variation. Some insects produce but one, two or three, while others, like the queen bee and white ant, lay thousands, and in case of the ant, millions.

_Larva of Bee._]

THE LARVA OF INSECTS.

From the egg comes the larva, also called grub, maggot, caterpillar, and very erroneously worm. These are worm-shaped (Fig. 12), usually have strong jaws, simple eyes, and the body plainly marked into ring divisions. Often as in case of some grubs, larval bees and maggots, there are no legs. In most grubs there are six legs, two to each of the three rings succeeding the head. Besides these, caterpillars have usually ten prop-legs farther back on the body, though a few--the loopers or measuring caterpillars--have only four or six, while the larvæ of the saw-flies have from twelve to sixteen of the false or prop-legs. The alimentary canal of larval insects is usually short, direct and quite simple, while the sex-organs are slightly if at all developed. The larvæ of insects are voracious eaters--indeed, their only work seems to be to eat and grow fat. As the entire growth occurs at this stage, their gormandizing habits are the more excusable. I have often been astonished at the amount of food that the insects in my breeding cases would consume. The length of time which insects remain as larvæ is very variable. The maggot revels in decaying meat but two or three days; the larval bee eats its rich pabulum for nearly a week; the apple-tree borer gnaws away for three years; while the seventeen-year cicada remains a larva for more than sixteen years, groping in darkness, and feeding on roots, only to come forth for a few days of hilarity, sunshine, and courtship. Surely, here is patience exceeding even that of Swammerdam. The name larva, meaning masked, was given to this stage by Linnæus, as the mature form of the insect is hidden, and cannot be even divined by the unlearned.

THE PUPA OF INSECTS.

In this stage the insect is in profound repose, as if resting after its long meal, the better to enjoy its active, sportive days--the joyous honey-moon--soon to come. In this stage the insect may look like a seed; as in the coarctate pupa of diptera, so familiar in the "flax-seed" state of the Hessian-fly, or in the pupa of the cheese-maggot or the meat-fly. This same form, with more or less modification, prevails in butterfly pupæ, called, because of their golden spots, chrysalids, and in the pupæ of moths. Other pupæ, as in case of bees (Fig. 13, _g_) and beetles, look not unlike the mature insect with its antennæ, legs, and wings closely bound to the body by a thin membrane, hence the name which Linné gave--referring to this condition--as the insect looks as if wrapped in swaddling clothes, the old cruel way of torturing the infant, as if it needed holding together. Aristotle called pupæ nymphs--a name now given to this stage in bees--which name was adopted by many entomologists of the seventeeth and eighteenth centuries. Inside the pupa skin great changes are in progress, for either by modifying the larval organs or developing parts entirely new, by use of the accumulated material stored by the larva during its prolonged banquet, the wonderful transformation from the sluggish, worm-like larva to the active, bird-like imago is accomplished.

_Pupa or Nymph of Bee, slightly magnified._]

Sometimes the pupa is surrounded by a silken cocoon, either thick, as the cocoon of some moths, or thin, as are the cocoons of bees. These cocoons are spun by the larvæ as their last toil before assuming the restful pupa state. The length of time in the pupa-stage is very various, lasting from a few days to as many months. Sometimes insects which are two-brooded remain as pupa but a few days in summer, while in winter they are months passing the quiescent period. Our cabbage-butterfly illustrates this peculiarity. Others, like the Hessian-fly and codling-moth, remain through the long, cold months as larvæ. How wonderful is this! The first brood of larvæ change to pupæ at once, the last brood, though the weather be just as hot, wait over inside the cocoon till the warm days of coming spring.

THE IMAGO STAGE.

This term refers to the last or winged form, and was given by Linné because the image of the insect is now real and not masked as when in the larva state. Now the insect has its full-formed legs and wings, its compound eyes, complex mouth-parts, and the fully developed sex-organs. In fact, the whole purpose of the insect now seems to be to reproduce itself. Many insects do not even eat, only flit in merry marriage mood for a brief space, when the male flees this life to be quickly followed by the female, she only waiting to place her eggs where the prospective infants may find suitable food. Some insects not only place their eggs, but feed and care for their young, as is true of ants, wasps and bees. Again, as in case of some species of ants and bees, abortive females perform all, or most of the labor in caring for the young. The life of the imago also varies much as to duration. Some live but for a day, others make merry for several days, while a few species live for months. Very few imagos survive the whole year.

INCOMPLETE TRANSFORMATIONS.

Some insects, like the bugs, lice, grasshoppers and locusts, are quite alike at all stages of growth, after leaving the egg. The only apparent difference is the smaller size and the absence or incomplete development of the wings in the larvæ and pupæ. The habits and structure from first to last seem to be much the same. Here, as before, the full development of the sex-organs occurs only in the imago.

ANATOMY AND PHYSIOLOGY OF THE HONEY-BEE.

With a knowledge of the anatomy and some glimpses of the physiology of insects in general, we shall now find it easy to learn the special anatomy and physiology of the highest insects of the order.

THREE KINDS OF BEES IN EACH FAMILY.

As we have already seen, a very remarkable feature in the economy of the honey-bee, described even by Aristotle, which is true of many other bees, and also of ants and many wasps, is the presence in each family of three distinct kinds, which differ in form, color, structure, size, habits and function. Thus we have the queen, a number of drones, and a far greater number of workers. Huber, Bevan, Munn and Kirby also speak of a fourth kind blacker than the usual workers. These are accidental, and are, as conclusively shown by Von Berlepsch, ordinary workers, more deeply colored by loss of hair, dampness, or some other atmospheric condition. American apiarists are too familiar with these black bees, for after our severe winters they prevail in the colony, and, as remarked by the noted Baron, "_They quickly_ disappear." Munn also tells of a fifth kind, with a top-knot, which appears at swarming seasons. I am at a great loss to know what he refers to, unless it be the pollen masses of the asclepias or milk-weed, which sometimes fasten to our bees and become a severe burden.

THE QUEEN BEE.

The queen (Fig. 14), although referred to as the mother bee, was called the king by Virgil, Pliny, and by writers as late as the last century, though in the ancient "Bee Master's Farewell," by John Hall, published in London in 1796, I find an admirable description of the queen bee, with her function correctly stated. Réaumur as quoted by "Wildman on Bees," published in London in 1770, says "this third sort has a grave and sedate walk, is armed with a sting, and is mother of all the others."

Huber, to whom every apiarist owes so much, and who, though blind, through the aid of his devoted wife and intelligent servant, Frances Burnens, developed so many interesting facts, demonstrated the fact of the queen's maternity. This author's work, second edition, published in Edinburgh, in 1808, gives a full history of his wonderful observations and experiments, and must ever rank with Langstroth as a classic, worthy of study by all.

_Queen Bee, magnified._]

The queen, then, is the mother bee, in other words, a fully developed female. Her ovaries (Fig. 11, _a, a_) are very large, nearly filling her long abdomen. The tubes already described as composing them are very numerous, while the spermatheca (Fig. 11, _e_) is plainly visible. This is muscular, receives abundant nerves, and thus, without doubt, may or may not be compressed to force the sperm cells in contact with the eggs as they pass by the duet. Leuckart estimates that the spermatheca will hold more than 25,000,000 spermatozoa.

The possession of the ovaries and attendant organs, is the chief structural peculiarity which marks the queen, as these are the characteristic marks of females among all animals. But she has other peculiarities worthy of mention She is longer than either drones or workers, being more than seven-eighths of an inch in length, and, with her long tapering abdomen, is not without real grace and beauty. The queen's mouth organs, too, are developed to a less degree than are those of the worker-bees. Her jaws (Fig. 21, _b_) or mandibles are weaker, with a rudimentary tooth, and her tongue or ligula (Fig. 15, _a_), as also the labial palpi (Fig. 15, _b_) and maxillæ are considerably shorter. Her eyes, like the same in the worker-bee (Fig. 5), are smaller than those of the drones, and do not meet above. So the three ocelli are situated above and between. The queen's wings, too, (Fig. 14) are relatively shorter than those either of the workers or drones, for instead of attaining to the end of the body, they reach but little beyond the third joint of the abdomen. The queen, though she has the characteristic posterior tibia and basal tarsus (Fig. 16, _p_), in respect to breadth, has not the cavity and surrounding hairs, which form the pollen baskets of the workers.

_Labium of Queen._

_a_--Ligula. _b_--Labial palpi.
_d, d_--Paraglossæ.
]

The queen possesses a sting (Fig. 11, _d_) which is longer than that of the workers, and resembles that of the bumble-bees in being curved, and that of bumble-bees and wasps in having few and short barbs--the little projections which point back like the barb of a fish-hook, and which, in case of the workers, prevent the withdrawing of the instrument, when once fairly inserted. While there are seven quite prominent barbs on each shaft of the worker's sting, there are only three on those of the queen, and these are very short, and, as in a worker's sting, they are successively shorter as we recede from the point of the weapon. Aristotle says that the queen will seldom use her sting, which I have found true. I have often tried to provoke a queen's anger, but never with any evidence of success. Neighbour (page 14, note) gives three cases where queens used their stings, in one of which cases she was disabled from farther egg-laying. She stings with slight effect.

_Part of Leg of Queen, magnified._

_t_--Tibia.
_p_--Broadened tibia and basal tarsus.
_t s_--Tarsal joints.
]

The queen, like the neuters, is developed from an impregnated egg, which, of course, could only come from a queen that had previously mated. These eggs are not placed in a horizontal cell, but in one specially prepared for their reception (Fig. 26, _i_). These queen cells are usually built on the edge of the comb, or around an opening in it, which is necessitated from their size and form, as usually the combs are too close together to permit their location elsewhere. These cells extend either vertically or diagonally downward, are composed of was mixed with pollen, and in size and form much resemble a pea-nut. The eggs must be placed in these cells, either by the queen or workers. Huber, who though blind had wondrous eyes, also witnessed the act. I have frequently seen eggs in these cells, and without exception in the exact position in which the queen always places her eggs in the other cells. John Hall, in the old work already referred to, whose descriptions, though penned so long ago, are wonderfully accurate, and indicate great care, candor, and conscientious truthfulness, asserts that the queen is five times as long laying a royal egg as she is the others. From the character of his work, and its early publication, I can but think that he had witnessed this rare sight. Some candid apiarists of our own time and country--E. Gallup among the rest--claim to have witnessed the act. The eggs are so well glued, and are so delicate, that, with Neighbour, I doubt the possibility of a removal. The opponents to this view base their belief on a supposed discord between the queen and neuters. This antagonism is inferred, and I have but little faith in the inference, or the argument from it. I know that when royal cells are to be torn down, and inchoate queens destroyed, the workers aid the queen in this destruction. I have also seen queens pass by unguarded queen-cells, and yet respect them. I have also seen several young queens dwelling amicably together in the same hive. Is it not probable that the bees are united in whatever is to be accomplished, and that when queens are to be destroyed all spring to the work, and when they are to live all regard them as sacred? It is true that the actions of bees are controlled and influenced by the surrounding conditions or circumstances, but I have yet to see satisfactory proof of the old theory that these conditions impress differently the queen and the workers. The conditions which lead to the building of queen-cells and the peopling of the same are--loss of queen, when a worker larva from one to four days old will be surrounded by a cell inability of a queen to lay impregnated eggs, her spermatheca having become emptied; great number of worker-bees in the hive; restricted quarters; the queen not having place to deposit eggs, or the workers little or no room to store honey and lack of ventilation, so that the hive becomes too close. These last three conditions are most likely to occur at times of great honey secretion.

A queen may be developed from an egg, or from a worker larva less than three days old. Mr. Doolittle has known queens to be reared from worker larvæ taken at four-and-a-half days from hatching. In this latter case, the cells adjacent to the one containing the selected larva are removed, and the larva surrounded by a royal cell. The development of the queen larva is much like that of the worker, soon to be detailed, except that it is more rapid, and is fed richer and more plenteous food, called royal jelly. This peculiar food, as also its use and abundance in the cell, was first described by Schirach, a Saxon clergyman, who wrote a work on bees in 1771. According to Hunter, this royal pabulum is richer in nitrogen than that of the common larvæ. It is thick, like rich cream; slightly yellow, and so abundant that the queen larva not only floats in it during all its period of growth, but quite a large amount remains after her queenship vacates the cell. We often find this royal jelly in incomplete queen-cells, without larvæ. Mr. Quinby suggests that this is stored for future use.