Warbles
Categories:
Diseases and their Remedies
It has been a prevalent opinion among farmers, that warbles are so many
evidences of the good condition of their cattle. It must, however, be
borne in mind that the warbles are the larvae of the oestrus bovis,
which is said to be the most beautiful variety of gad-fly. This fly,
judging from the objects of its attack, must be particularly choice in
its selection of animals upon which to deposit its eggs, as it rarely
ch
oses those poor in flesh, or in an unhealthy condition. From this
circumstance, probably, has arisen the opinion above-mentioned.
These warbles--or larvae of the oestrus bovis--so nearly resemble
bots in the horse--or larvae oestrus equi--that, were it not for
their increased size, they might readily be mistaken the one for the
other. There is, however, one other difference, and that is in the rings
which encircle the body; those of the former being perfectly smooth,
while those of the latter are prickly, and from one third to one half
smaller.
The author was called, in the year 1856, to see the prize cow, Pet,
belonging to James Kelly, of Cleveland, Ohio, whose extraordinary yield
of butter and milk had been reported in the Ohio Farmer, a short time
previous to his visit. This animal was found by him in rather poor
condition; the causes of which he could only trace to the existence of
these worms, comfortably located, as they were, beneath the animal's
hide, and forming small tumors all along the spinal column, each being
surrounded by a considerable quantity of pus. A number of these were
removed by means of a curved bistoury and a pair of forceps, since which
time--as he has been informed--the animal has rapidly improved,
regaining her former good condition.
Some may urge that this is an isolated case; but an examination of
cattle for themselves, will convince them to the contrary. It may be
added, that two other cows, belonging to the same gentleman, were also
examined at the same time,--one of them being in good condition, and the
other, out of condition. From the back of the latter several of these
insects were removed, since which time she also has much improved. The
former was entirely free from them. These cows were all kept in the same
pasture, received the same care, and were fed on the same food, and at
the same time; and as the removal of these larvae has been productive of
such beneficial results, have we not a right to infer that these insects
are injurious?
If we go further and examine, in the spring of the year, all cattle
which are subject to them, instead of finding them in the fine
condition which one would naturally expect,--considering the abundance
of fresh young grass whose vigorous life they may incorporate into their
own,--they are out of condition, and out of spirits, with a laggard eye,
a rough coat, and, in some cases, a staggering gait, as though their
strength had failed in consequence.
How shall such attacks be prevented? During the months of August and
September this gad-fly is busily engaged in depositing its eggs. Some
are of the opinion that they are placed on the hairs of the animal;
others, that the skin is perforated, and the egg deposited in the
opening, which would account for the apparent pain manifested by cattle
at and after the time of such deposit. Be this as it may, it is certain
that the maggot works its way into the muscular fibre of the back, and
depends upon the animal's blood for the nourishment which it receives.
The author has been informed, by persons in whom he ought to have
confidence, that the free use of the card, during the above-named
months, is a specific protection against the attacks of the oestrus
bovis. He repeats this information here, not without diffidence; since
so large a majority of stock-owners evince, by their lack of familiarity
with the practical use of this convenient and portable instrument, an
utter disbelief in its reliability and value.