CHAPTER XVI
THE ENEMIES AND DISEASES OF BEES
THE BEE-MOTH (Galleria mellonella)
This miserable little pest is classic in its devastations as it is mentioned by the old writers, Aristotle paying to it bitter tribute. It belongs to a family of secretive moths which fold their dull wings closely about the body, and thus look more like bits of sticks than like insects. They are called the snout moths (Pyralidæ) because the palpi extend out in front of the head in a highly ornamental and striking manner.
The bee-moth is a most insidious creature, hiding in cracks, and, when it flies, darting about with almost inconceivable swiftness. It is only by such means that it eludes the watchful bees. Professor Kellogg observes that the moth simply works against time when it rushes into a hive by laying its eggs rapidly, dodging about with the utmost rapidity to leave as many progeny as possible before the bees can get hold of her and tear her asunder, a fate which surely awaits her. So it seems that even a parasite may be brave and go to certain death in fulfilling its destiny. Mr. Cook says that the moth will lay eggs while her head and thorax are being dissected, which shows that even after death she is efficient for mischief in the hive.
The eggs are small and white and are put into crevices. From such an egg there hatches a caterpillar which spins about itself a silken tube, wherein it lives and in some mysterious way is protected from the bees. It may be that these tubes are of such texture that the bees cannot sting through them; or they may simply be sufficiently thick to protect their inmate from bee observation. The caterpillar lives upon the wax and young bees, and also upon the bee bread; it is a voracious eater, and tunnels through the comb, destroying everything in its path. Those who have had experience with it say that by holding an infested comb to the ear, the noise made by the industrious jaws of the caterpillar can be distinctly heard. Its presence can be detected by the filth and the débris on the bottom board of the hive and also by the silken tubes on the comb. When the caterpillars destroy the bee larvæ, the bees take out the remains and dump them in front of the hive, thus gaining among the ignorant, a reputation for infanticide which they little deserve.
In favourable locations the growth of these moths from egg to adult may require six weeks; the caterpillar when about an inch in length changes to a pupa, in a very thick, protecting cocoon of tough silk. The silk made by these caterpillars is of a most excellent quality; there is in the Cornell University Museum a filmy but strong silken handkerchief made by bee-moths passing and repassing over a flat board; it was made quite involuntarily as the caterpillars spin wherever they go. The bee-moth is especially destructive to stored comb if it is piled close together.
REMEDY
To prevent the injuries of this pest the colonies should be kept strong. The bee-moth follows the rule of other parasites and attacks only the weak and the irresolute, and never injures a comb that is covered with bees. A queenless colony, dejected and discouraged, is usually victimised by it. The Italian bees have learned to cope with the bee-moth and exterminate it whenever attacked by it. Some bee-keepers, when a comb becomes infested, introduce it into the centre of an Italian colony, being sure that the little wretches will find there the fate they deserve. But to us this seems rather an imposition upon a self-respecting colony of bees.
The use of plain, simple, well-made hives is a protection from the bee-moth, as such hives do not afford hiding-places for moths and eggs.
Before comb is stored it should be put in a closed box out of doors, and a saucer of carbon bisulphide placed on top of the comb and left for a day. The deadly gas of this poison is heavier than the air and so falls instead of rising. Care should be taken not to breathe the fumes more than is necessary and hence the work should be done in the open air. Another reason for this is that the gas is inflammable, and hence no fire should be allowed near it. There is another reason why the work should be done in the open and that is because of the sickening stench of the gas. Comb thus treated should be stored in a perfectly tight receptacle, or else be set an inch or so apart on shelves. The bee-moth caterpillar does not seem to like to work in combs that are not set as closely together, as they are in the hives.
If combs infested with the bee-moth are subjected to a temperature of 10° F. the moth is usually exterminated. However, the pest normally passes the winter in the pupa state, and seems to be able to survive in hives left out of doors, wherever the bees can survive. It should be remembered that the bee-moth works only during the summer from May until October, and remains quiescent during the winter. As a matter of fact the modern up-to-date bee-keeper has almost no trouble with the bee-moth. It is a special enemy of the heedless and careless man who neglects his hives, and thus may well deserve to have his bees exterminated.
If a colony is attacked by the bee-moth, the hive should be thoroughly cleaned; new good comb should be introduced and only enough so that the bees can cover it. The infested comb should be fumigated with carbon bisulphide, and after the moths are killed it may be given to a strong colony to clean out and use.
THE INDIAN-MEAL MOTH (Plodia interpunctella)
The Indian-meal moth sometimes forsakes its bins of grain and meal and devastates the honeycomb. It does not measure more than one-eighth of an inch across its wings, and its caterpillar is almost too small to be noticed, unless it occurs in great numbers. It sometimes attacks the honey-comb in the North, and in the South it is often a great nuisance. The only remedy for this very small pest is to change the bees to smaller hives, and expose the infested comb to the fumes of carbon bisulphide.
BEE-MOTH MAXIMS
The shiftless bee-keeper is the one who complains of the wax-worm.
Keep Italian bees.
Keep the colonies strong.
Do not leave more comb in the hive than the bees are able to cover.
Use well-made hives with no crevices.
If you see a web upon the comb, hunt out the caterpillar and kill it at once.
If bee-moths get into the honey store-room, close the room and fumigate it with brimstone or carbon bisulphide.
FOUL BROOD
This is an infectious bacterial disease, and its presence in the apiary may be attended by serious results. When it first appeared in America, large apiaries were completely destroyed. In 1874, Professor Cohn discovered the organism which causes the disease, and which bears the name of Bacillus alvei. This microbe attacks the immature larvæ and they die in the cells. It always attacks, to a lesser extent, the adult bee; but these leave the hive to die and are not such a dangerous source of infection as are the decaying larvæ. Infected honey is the medium by which the disease is ordinarily spread from hive to hive. Undoubtedly robbing is to a great extent responsible for its prevalence.
HOW TO DETECT FOUL BROOD
The brood appears in irregular patches and it does not all hatch; the caps to the brood cells may be sunken and broken at the centre, the holes being irregular, instead of the neat circular perforations which may be found above the healthy larvae. The sure test of the presence of the disease is found in the dead body of the larva, which is dark and discoloured; and if a toothpick or pin be thrust into it and then drawn back, the body contents will adhere to it in a stringy mass, to the extent of a half or even an entire inch, as if it were mucous or glue; later the bodies of the larvae dry and appear as black scales in the cell bottoms. Another evidence of the presence of the disease is a peculiarly disagreeable odour which permeates the hive, which Mr. Root likens to that of a glue pot.
Remedies.—These have been worked out by many bee-keepers, notably by Mr. William McEvoy, inspector of bees in Ontario, Canada. His remedy is as follows: When there is a good honey flow so the bees will not suffer, all the comb is taken from the infected colony and frames with foundationstarters are given instead. Having no young to feed, the bees use all the infected honey in their stomachs for making comb. At the end of the fourth day all this comb is removed and new-frames with foundation are substituted, and the deed is done.
Mr. Root's practice is to remove the hive from its stand about dark, to prevent robbing, and put another just like it in its place which contains frames filled with foundation. The bees are shaken from the infected hive into the new one. Here they are shut in without food for three or four days, thus being compelled to use all the honey in their honey sacs. Then they are fed and the disease does not appear again in colonies thus treated. Mr. Root burns all the infected comb and frames and disinfects the hives with hot water before they are used again; other apiarists of experience support Mr. Root in this matter. Fumigating the hives with burning brimstone would perhaps be an easier or a surer way of disinfecting the hives.
Many apiarists who do a large business do not destroy the infected comb, but render it in a steam wax press. They also thin the infected honey and boil it for two hours, adding to it a little salicylic acid, and use it to feed back to the bees. But this would hardly pay, unless great care were taken, as one drop of the infected honey would start the disease anew.
Some have tried medicated syrup as a remedy. It is true that syrup made with salicylic acid or betanaphthol will retard the disease, but most bee-keepers believe that it is not a sure remedy.
BLACK BROOD
This appeared in New York so frequently that it was called the New York bee-disease. It was differentiated from foul brood by Dr. Wm. R. Howard, of Texas, who found the bacillus and described it. The chief way of telling it from foul brood is that the contents of the body of the dead larva is jelly-like, instead of gluey. However, Dr. Veranus Moore and Dr. G. Franklin White, of the New York Veterinary College at Cornell University, worked upon this disease for some time and, in 1903, reported that the bacillus of this disease is alvei and identical with that discovered and disscribed by Cohn as the cause of foul brood.
PICKLED BROOD
This disease of the brood differs from the others in that the body-contents of the dead larva are watery and that no peculiar stench in the hive emanates from them. Neither is it so contagious as foul brood, though it may seriously cripple an apiary, if not checked. The remedy for foul brood is applied with success to colonies suffering from this disease.
DIARRHOEA
This disease is part of the difficulty of wintering. It is induced by the bees' habit of retaining waste matter in the body until they can fly out of the hive, for thus they preserve the cleanliness of their home. The first symptom of the disease is the soiling of the hive entrance with brownish excrement; the bees are also likely to die in great numbers, their bodies being much swollen.
The cause of the disease is attributed to cold and dampness, and poor food. If, in the fall, the bees store honey made from the juices of rotting fruit or cider refuse, or from honey-dew excreted by plant lice, they are very likely to perish by feeding upon it during the winter. But even with good honey bees wintered in cold, damp hives are liable to contract the disease.
PREVENTION