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The sheep gad-fly, Cephalemyia Ovis, Linn., is somewhat smaller 
than the species above noticed. Its thorax is grayish and is covered 
with little black tubercles, each of which bears a hair. The abdomen 
is white and in particular reflections of the light exhibits irregular black 
spots. The legs are yellow and the wings hyaline. This fly common¬ 
ly lurks about the vicinity of woods, in the months of June and July. 
According to the accounts of it that we meet with in authors, it aims 
to get its eggs within the nostril of the sheep, and for this purpose darts 
upon it with the quickness of lightning, depositing an egg in the act. 
The warmth and moisture of the part speedily hatch this egg, and the 
little worm that comes from it crawls up the nostril until it reaches 
some of the cavities connected with the nose. It is said that this worm 
occasions great irritation as it crawls upwards, causing the poor animal 
to gallop furiously about, snorting violently, as if almost maddened by 
the annoyance. The worm commonly takes up its abode in the frontal 
sinuses. These are two large shallow cavities in the forehead, one on 
each side, directly above the eyes and the root of the nose. It here 
fastens itself, by means of two hooks with which it is provided, to the 
skin which lines these cavities, and there remains until April or May 
in the following year, the sheep experiencing no further annoyance 
from it after it attaches itself. Being at length fully grown, it loosens 
itself from its hold upon the skin and crawls out the same way by 
which it entered, again giving much annoyance to the animal, which 
makes most violent efforts to sneeze it out. Dropping to the ground, it 
burrows beneath the surface, and becomes an oval, motionless pupa, in 
which state it remains six or eight weeks, when, breaking asunder its 
its shell, it comes forth a perfect fly. Being destitute of a mouth it 
takes no food, and only exists a short time, depositing its eggs for an¬ 
other generation being its sole employment. 
I am informed by my neighbor, John McDonald, that some years 
since a number of his sheep were observed in the month of April to be 
affected with a discharge of mucus from the nose. They lost their ap¬ 
petite, pined away and became quite emaciated, and about a half dozen 
of them died. On opening the heads of these, from one to six grubs 
were found in the frontal sinuses of each. I have never examined the 
heads of deceased sheep to find the larva of this insect, but have, in 
some instances, observed it dead in the mucus that oozed from the nos¬ 
trils of the sheep, a day or two after it had died. And from this fact 
I infer that like other parasites, it leaves the body on which it has 
preyed when life has become extinct, and those larvaj that are suffi- 
