The Washburn times. [volume] (Washburn, Wis.) 1896-1976, 1916-03-09

(From Weekly News Letter United States
Department of Agriculture.)
| Specialists of the department are
urging cattle owners, in the North as
well as in the South, to take steps to
rid their cattle of OK MARBLES or
wolves" the Importance of which to
the cattle industry has been generally
underestimated. Ok MARBLES are the
whitish grubs or maggots which de-
velop from the eggs deposited by GER
tain flies known as MARBLE flies or
heel flies, and which injure the hides,
reduce milk flow and retard the growth
Of the animals. The maggots are COM
monty found just below the skin on
the backs of cattle in the spring. Their
presence is revealed by local swellings
about the size of pigeons eggs, each
with a small central hole or perfora-
ton through which the maggot
breathes. From this hole the maggot,
when mature, energies to enter the
ground and change to the adult or fly
stage. When full grown the grub is
about three-fourths Of an inch in
length.
In the past trouble from the MARBLES
has largely been confined to cattle in
the South, but recently the bureau of
entomology has discovered that Sec
ond species, heretofore not found in
this country but known to be even a
more serious pest in Europe than is
our native MARBLE, has become well es-
tablished in certain districts in the
northern part of the United States.
While it is probable that this so-called
European OK MARBLE will not be of as
great Importance in the southern part
of the United States as the species al
ready established, there is every rea'
son to believe that unless checked it
will become generally distributed
throughout the northern half of the
country. This European species is
now generally distributed throughout
New York and the New England states
and a few specimens have been OBJ
tanned from western Pennsylvania,
| western Maryland, southern Michigan,
eastern Iowa and Missouri, and west
ern Washington. Attention is also di-
rected to the fact that this species is
new generally distributed throughout
southern Canada. The department,
| therefore, is calling attention at this
time to the danger of spreading this
| species promiscuously about the coun-
| try, and is urging cattle owners to take
| the simple means necessary to pre-
vent it's spread.
Until recently MARBLES we're not re-
garded as serious even in the South,
because it was thought that the loss
they occasioned came principally from
the damage they did to hides. Even
this loss in the aggregate, however, is
important, as hides show MARBLE holes
three to six months in the year, and
dealers pay from 80 cents to $1.50 less
for hides that show even moderate
MARBLE infestation. In many cases the
scars left after the holes have healed
cause buyers to cut prices consiC-
erably.
The loss from the MARBLE, however,
is by no means limited to the holes the
maggots cut in the hides. Extensive
investigations in Germany and Den
mark indicate that the losses through
reduction in milk supply in dairy cat
tie, the retardation of growth in young
stock, and the loss of flesh in all
classes of animals are twofold greater
| than the damage done to the hides. II
some of these tests the early extrac-
| ton of the grubs from the backs of in
| tested cattle resulted in an increase of
nearly 25 per cent in the milk produc-
ton. Animals from which the grubs
had been extracted showed a gain of
more than five per cent in weight over
similar animals in which the pests
were allowed to develop normally.
Thus far the veterinarians and en-
tomologists of the department have
determined no better way of control
ling these pests than through the sys-
tematic extraction and destruction of
the grubs from the backs of infested
animals.
| When the larvae are nearly ready to
leave their host they may be easily
squeezed out by pressing the swelling
with the fingers, but if not so far de-
veloped it is often very difficult to get
them out by squeezing. In such cases
slender pair of forceps may be used
for pulling them out. If the swelling
and its opening are still very small,
the best way of extracting the grub is
to make an incision with knife, after
which the grub can be squeezed out by
applying strong pressure. Kill the grub
when removed.
1t is important that MARBLES be re-
moved as early in their development
as possible. This relieves the infested
| animal from the irritation and pre-
vents the enlargement of the exit
holes. While this practice is not APP
plicable to ranch conditions, it is
| >oo>@o>~~~~~s~