62 
Bat at present we are concerned only wich the history and habits 
of the species which infests sheep. As a general, and until recently 
supposed universal, rule, the flies deposit eggs from which the mag¬ 
gots are hatched. But recently Prof. Riley, on the authority of Mr. 
Cockrill (who produces the statements of two other witnesses), and 
some facts known in regard to the habits of this species, arrives at 
the conclusion that it deposits living young. While the usual habits 
of the species of this family appear to be opposed" to this idea, 
and the great difficulty of making direct observations might lead us 
to doubt the correctness of this conclusion, yet it is well known to 
entomologists that similar departures from normal habits do occur 
among insects, and the difficulty of the egg maintaining its situation 
until hatched would seem to favor this idea. Repeated dissections of 
gravid females would appear to be the only feasible means of determ¬ 
ining this question. This appears, from Prof. Riley’s statement, to 
have been done in two instances, showing living young. The parent 
fly deposits her eggs or larvae, as the case may be, in the nostrils of 
the sheep. As soon as the larvae are deposited or hatched, they at 
once commence to make their way up the nostrils to the frontal sinu¬ 
ses, causing great irritation to the lining membrane; here they attach 
themselves firmly by the little hooks with which the mouth is furnish¬ 
ed, and feed on the mucus which is always found here. While young 
they are of a creamy-white color, except two brown spots on the hind 
segments, which are the breathing pores. When full-grown they are 
darker, varying from a dirty-white to a brown, the hinder portion be¬ 
ing darker than the front; these differences in color represent, more 
or less distinctly, rings corresponding with the segments, not reach¬ 
ing around the body, but leaving a pale space along each side, which 
is marked by a row of brownish dots, representing the breathing pores. 
The under side is marked between the ventral rings with bands of 
minute dots or tubercles, which are tipped with little short spines, 
which, if examined with a magnifier, are found to be of a reddish 
color, and to point backward. It is now shaped somewhat like a beet, 
largest behind, and tapering to the head, which is quite small. Kollar 
states that it is without the ventral spines usually found in the larvae of 
this group of insects, but, although minute and not easily seen, they 
are, nevertheless, present, for without them we could hardly explain its 
power of moving forward on the unctious mucous membrane. 
Having entered the nostrils in the middle of the summer, worked 
its way to the frontal sinuses, and gradually attained its full growth, 
it remains here until the following spring, when it loosens its hold 
and works its way down the nose, producing great irritation in the 
membrane and uneasiness in the animal, and drops to the ground. It 
rapidly burrows into the soil out of view, and in a short time, two 
or three days at most, transforms into a chrysalis. It remains in this 
state six or eight weeks, and then comes forth from its hiding-place 
a true two-winged fly, somewhat larger than the common house-fly, 
but resembling it in general appearance. The head and thorax are 
brownish; the abdomen consists of five segments, or rings, which are 
velvety, and variegated with brown and dull yellow, or, as Youatt has 
expressed it, “tiger-colored on the back, being prettily striped and 
marked.” 
As before stated, its mouth is so imperfect and undeveloped, that it 
may be said to have none. It is, therefore, wholly unable to imbibe 
