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were seriously affected by the ravages of an insect pest known as "Warbles."
The question was considered to be one of importance, both to the Army Boot
and Ordnance Saddlery Factory, as well as to the large export trade in raw
hides. It was therefore asked that the services of Dr. Lingard, the Imperial
Bacteriologist, might be lent for the purpose of making an enquiry into the
whole matter, but with particular reference to finding a remedy, the applica-
tion of which would prevent the fly from attacking the animals.
622. Dr. Lingard's services for this investigation could not be spared
from his more important laboratory work, but he extracted some important
information bearing on the life history from the standard works on the subject,
and this was submitted to the Government of India with this Office letter
No. 286-227 R. & A., dated the 5th October 1898. As some of these extracts
are considered important as detailing the life history of this pest it has been
deemed advisable to give some of them later.
623. That this subject is an important one will be at once evident from
the fact that the annual export of hides is something like ten millions, but
whether with our limited staff we shall be able to cope with the ravages of
this pest to any great extent is another question. However, it was certainly
a matter with which the Civil Veterinary Department was intimately connect-
ed, and with the object of obtaining all available information on the subject,
the several officers of the Civil Veterinary Department had their special atten-
tion drawn to the pest, and they were desired to make careful investigations
as to the habits of the Gad fly in each Province, and to ascertain whether the
people were acquainted with the cause of the "Warbles", and whether they
employed any medicaments to prevent it. In addition to the Veterinary
Superintendents, other officers connected with Agriculture were asked to
kindly use their best efforts in gaining information on the subject, and my
best thanks are due to them for their contributions. In their notes there
seemed to have been some confusion, however, between the Gad fly (Hypoderma
bovis) and the large fly (Lucilia Cœsar) which deposits its eggs in wounds.
These latter cause little or no harm, if carefully treated, and do not destroy
the hides, and so long as there is no wound or abrasion the animal is perfectly
safe from attack. It is quite a different matter with the Gad fly which deposits
its eggs on the backs of animals, and which are practically imperceptible until
the larvæ increase in size and form a visible tumour under the skin.
624. The following brief description of the fly will be useful in enabling
investigators to distinguish the "Ox Hypoderma" from other species :—
"Black, very hairy. Face grey, with white or yellow hairs, similar hairs in front half of the upper
surface of the thorax, black on the back part, close together Abdomen black covered with white or yellow
hairs at its base, black in the middle, reddish orange in its posterior third. Legs black at the base, yellow in
their terminal moiety, wings somewhat brown. Length, exclusive of ovipositor, 13 to 15 m. m."
625. The female is provided with a soft, short, black, cylindrical oviscapt,
which is folded beneath when the insect is resting, and which serves to deposit
its eggs on the skin of cattle while they are grazing. It prefers the upper
parts of the bodies—the shoulders, back, loins, croup and occasionally sides
and flanks. Its flight is rapid and accompanied by a buzzing sound. When
it is about to lay its eggs, it flutters above the animal's back for a minute or
two, then suddenly drops, deposits an egg on the skin, rises in the air, again
flutters, descends with the like rapidity as before, and drops another egg.
This manœuvre is repeated 10 or 12 times during a half an hour.
626. The eggs are white, elongated and somewhat flattened, but the first
stage of development does not seem to have been accurately observed. In the
second stage—which occurs about August—the larva is club-shaped. As,
however, the description of these stages are not of special interest to the
general reader they are omitted. We therefore pass on to the more practical
information regarding the larval existence. This is passed beneath the skin
of the host, in the subcutaneous connective tissue. In the earlier period no
irritation is remarked around the parasites ; but during the end of the cold
weather the presence of the larvæ is made manifest externally by tumours, the
size of which increases with the development of the parasites. The number of
tumours is variable; there are rarely fewer than five, and usually there are ten
or twenty, and sometimes as many as fifty and even more. They are of unequal