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 honey-comb. 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 larvæ. 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 larvæ 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
foundation-starters 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 beta-naphthol 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 described 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
Give the bees plenty of good food for winter. If the honey they have
gathered in August is extracted, feed them syrup from the best of
sugar. In winter keep the hives in proper temperature, with sufficient
good air and ventilation. After the disease once appears, there is no
remedy, except warm weather, which will promptly bring relief.