How far the diseases of domesticated animals are due to the conditions to which they are subjected by man, and which are always, to some extent, contrary to the natural mode of life of the creatures, we are at present unable to say. We can, however, point with some certainty to cases in which birds and quadrupeds, which are made subservient to our needs or our convenience, suffer in consequence of our treatment. In some degree, this is true with regard to bees. In a wild state their habitations may, indeed, expose them to risks they do not run in hives, but these artificial dwellings, on the other hand, tend to the development, or the extension of, at least two maladies to which their occupants are subject. These are the deadly evils of dysentery and so-called "foul-brood."

Dysentery has been known in apiaries from the time of Columella, in the first century of our era, who attributed it to the effect of food derived by the bees from the elm and the spurge. Other more recent writers have ascribed it to over-indulgence in spring-honey, wheresoever derived: others, again, to the consumption of stores which had candied in the cells during the winter. More recent investigations show that there are several means by which this trouble may be generated. In the first place, ineffective ventilation, by permitting the condensation of moisture on the combs, and its admixture with the food stores, is a prolific source of the mischief. During the winter, the low temperature is constantly reducing to a watery condition the aqueous vapour given off by respiration. This vapour, like our own perspiration, contains matter derived from impurities in the circulating fluid, and is the natural vehicle for their removal. If, then, such moisture again enters the body of the bee, it is simply a poison, whose effects become manifest by producing diarrhœa, distension of the abdomen, and more or less speedy death.

Again, if the stocks be supplied in the late autumn with syrup too watery for the bees to seal over in the cells, contact with air sets up a chemical change, and a certain amount of acid is generated, which makes the honey most prejudicial to the health of the stock, by deranging their digestive functions.

Thirdly, if during the winter time, when the insects are closely confined to their dwellings by the weather, and when they are, under ordinary conditions, very quiescent, they be disturbed and excited, they are apt to gorge themselves with food; and having no natural means of working off the extra quantity they have taken, the system is overloaded, and the stomach and intestines suffer from the too great burden thrown on them.

The occurrence of this malady is indicated by the altered appearance and odour of the excrement, which, instead of being reddish yellow, becomes of a muddy black colour, and has an intolerably foul smell. It is, moreover, deposited by the weakened insects, contrary to their cleanly habits, on the combs, the inner walls of the hives, on the floor-board, and at the entrance of their dwellings.

The avoidance of the causes of the generation of the disease is a comparatively easy matter. The means of cure are, first, the removal of the reasons for its occurrence, and, secondly, the immediate and thorough cleansing of all parts of a hive soiled by the sick bees. It is still better, if possible, to remove the stock into a perfectly fresh dwelling; and it is advisable to take away all combs with unsealed honey, and substitute sealed stores, or to feed the bees with barley-sugar.

"Foul-brood" is a much more formidable malady, and is often encountered. It is, indeed, a terror to apiarians, for not only is it very fatal to any stock in which it appears, but, from its ready contagiousness, it may depopulate any number of previously healthy communities, and may extend from one apiary to several others in the neighbourhood.

As the name implies, it has been thought to be a disease of the larvæ, and there are said to be two kinds, called respectively the dry and the wet. The former of these is much less serious, and is not contagious. The young merely die in their cells; their bodies desiccate, and there is an end of the matter. In the other variety, the brood remains dark and shiny in the hatching-places, and emits a most offensive odour, perceptible at some distance from the hive. When the mischief is very great, combs are sometimes removed which are masses of corruption and fœtor.

Microscopical investigations led to the belief that the source of this dire pest was a microbe, allied to micrococcus. If the germs of this lowly organism find a lodgment on the tender skin of a larva, they propagate with immense rapidity, and cause the death of the young insect. Then, wafted about the hive by the currents produced in ventilation, they pass from one part to another; or, attaching themselves to the bodies of adult bees, they are carried from cell to cell, and each of these thus infected, in its turn, becomes a new centre of deadly plague.

Dr. Schönfeld in Germany made a series of interesting experiments, which he considered conclusive on the question of the origin and spread of this disease. From a small piece of foul-brood he propagated, by suitable means, large quantities of the fatal so-called micrococcus, and with it he was able to infect a healthy stock. He, moreover, established the fact that the dried germs float readily in the air. Placing some of the foul-brood in a bell-glass, in which he inserted lightly a plug of cotton-wool, he caused a gentle atmospheric current to pass into the glass, and out by the tube. Then, moistening the cotton-wool with water, and putting some of the liquid under a microscope, he detected what he concluded to be numerous spores.

This circumstance throws a light on the contamination of the different hives in an apiary, through one that has become infected; as, no doubt, during the process of ventilation, many germs of the disease find their way out of the entrances. It is probable that robber-bees are also very frequently the carriers of contagion. Taking advantage of the dwindling down of a stock suffering from the disease, these plunderers pilfer the honey, and, in so doing, receive on their bodies the fatal seeds of the malady, which they then carry to their own stocks. In this way the existence of the pest in one community may become the cause of its extension throughout a neighbourhood. It is, therefore, of the utmost importance that the signs of the appearance of the evil should be constantly watched, and very stringent measures applied whenever its existence is ascertained.

Until quite lately it was thought that no means of cure, strictly so called, existed. The germs are so minute, and are capable of such diffusion and adherence in a hive, that half-measures proved, as usual, of no avail. The removal of the combs and bees to a fresh hive, and thoroughly sprinkling them with salicilic acid and water, has been recommended as a remedial course; but bee-keepers found that nothing short of the complete destruction of the infected community was likely to be really effective, and the first loss, in such a case, might save the entire destruction of all the stocks in the apiary. The very honey stored in the combs had to be sacrificed also; for in it the dangerous germs settle, and being used by the nurse-bees for feeding the larvæ, become the continued, and possibly unsuspected, source of mischief to any hive to which it is imparted. If the disease appeared in a straw skep, it was considered desirable to destroy it with fire. If it found its way into a bar-frame hive, every frame, every portion, even every crevice, must be treated. Thorough boiling in a copper has been found helpful in eradicating the mischief, but could not alone be relied upon. A strong mixture of chloride of lime and water, or of salicilic acid and water, applied carefully to every part, has been found more effective. The important facts to be remembered are that, owing to the extreme minuteness of the germs, their multitudes, and their great vitality, it is very easy for some to escape destruction, and to become the sources of future mischief, unless the most radical methods of destruction are applied to them.

A new light has, however, just been thrown on this important subject by Mr. Frank Cheshire, of Acton, who has done so much good work in the anatomy of bees, and in their practical management. He has now satisfied himself, by long-continued and careful microscopic investigation, that the origin of foul-brood is a bacillus, not a micrococcus,[5] and that the disease extends to all the inmates of the hive. But what is of far greater moment to apiarians is, that Mr. Cheshire claims to have discovered a means of completely curing the dire plague. This consists in the administration of phenol, which is one of the components of carbolic acid. Syrup is made with 3 lbs. of loaf-sugar to a quart of water, and to this is added ¹/₅₀₀ part of pure phenol. By removing the stored honey, and pouring the syrup into cells around the infected parts of combs containing foul-brood, the bees are induced to consume the medicated food. The "nurses" supply it also to the larvæ, and the result is, that not only is the progress of the disease stopped, but renewed courage and hope are infused into the community, who remove the dead larvæ, clear out the polluted cells, and bring about an entire renewal of healthy conditions. Should further facts prove all that Mr. Cheshire expects, he will be regarded by apiarians in future with as much admiration as Jenner, the introducer of vaccination, is looked upon by the medical world. His generous publication of his discoveries, so that all interested may have the benefit of them, lays all bee-keepers under great obligations to him.

As an example of the terrible results of this pest to the bee-keeper, the case of the well-known German bee-master, Dzierzon, may be mentioned. In the year 1848 the disease broke out in his apiary, and more than 500 stocks were destroyed by it; in fact, only ten hives escaped the pestilence. John Hunter—the author of a good Manual of Bee-Keeping—records that from a friend, who had complained of not finding his bees profitable, he purchased all his stocks, some twenty in number, and removed them to his garden. They proved to have foul-brood in them, and not only did the whole of them perish, but all Mr. Hunter's own stocks, and, in addition, two or three years of trouble were required to eradicate the mischief from the apiary.

The late Mr. Woodbury, whose name is "a household word" among bee-keepers, was unfortunate enough to have this disease among his hives in the spring and summer of 1863. He published a graphic account of his trouble in the Journal of Horticulture of July 21st, 1863, entitled, "A Dwindling Apiary." By very vigorous measures he was able to get rid of the pest; but the conclusions to which he came were the following: "First let me endorse the opinions of both Dzierzon and Rothe, that, except under very especial circumstances, it is unadvisable to attempt the cure of a foul-broody stock: better, far better, to consign its inhabitants to the brimstone-pit: the hive itself, if a straw one, to the flames: the comb to the melting-pot: and appropriate the honey to any purpose except that of feeding bees."

It is now known that this treatment is by no means always successful when the bacilli have reached the "resting" or "spore" stage.

The detection of signs of the disease is not very difficult, especially in hives with movable frames. If, during the working season, a stock seems not only not to increase, but to diminish in numbers; if fewer and fewer bees appear active about the entrance; and if, above all, a peculiarly disagreeable odour is perceptible, at even one or two feet from the entrance, it is time to look to the condition of the interior. An infected comb, on examination, is seen to be dark and unwholesome-looking. If the caps covering the brood be distinctly sunk, so as to show a concave surface, the existence of the disease is almost a certainty; and if the covering of one or more of these cells be removed, there will be found dark coffee-coloured, slimy liquid, the remains of the larvæ destroyed by the bacillus.

From what we have said of this disease it will be seen that it is most important for any one about to commence bee-keeping to be sure the stocks he may purchase are not only themselves free from disease, but come from an apiary absolutely uninfected by it. Many a beginner in apiculture has been so disheartened, and has suffered such severe loss from foul-brood in his hives, that he has given up bee-keeping in disgust. We need hardly say that any man who knowingly sold hives with foul-brood in them, would deserve to be visited with penalties for damages, which we have no doubt his victim could obtain by legal process.

Some writers enumerate vertigo, or giddiness and staggering, among the diseases of bees. We incline to the belief that cases of the kind observed were due to the individuals having been stung in fighting, though it is possible that mistakes in pasturage may occasionally be made, and that the nectar of certain flowers may induce disorder in the bee-constitution. We, however, doubt the likelihood of the quick senses of the insect being at fault with regard to food which will prove hurtful.

One other malady has been occasionally noticed, viz., the swelling of the terminal segments of the antennæ. The occurrence of this mischief is too rare to need further remark, beyond the suggestion that it may be the result of microbe germs having made a lodgment in the tender organs affected.

There is a striking analogy in the results of insanitary conditions, and the propagation of zymotic disease among the human family and among bees. Unwholesome food, defective ventilation, the diffusion of poisonous germs, produce, among both orders of beings, similar disastrous effects; and this sketch of the diseases of one class of domesticated insects may serve to point a moral for the guidance of mankind in social economy. The same inexorable laws of health and sickness prevail in the highest and the inferior orders of animal existences, and with unvarying steadfastness is proclaimed the solemn warning "Be not deceived: God is not mocked. Whatsoever a man soweth that shall he also reap."