316 
SUMMARY AND CONCLUSIONS. 
The facts here recorded, in the light of the hitherto universally ac- 
cepted views in reference to the life-history of the Ox Bot, are ex- 
tremely interesting. They may be summarized as follows: 
In North America, so far as we yet know, Hypo- 
derma bovis does not oceur. Considering the fre- 
quency with which cattle have been imported into 
this country from abroad this fact seems almost in- 
credible, yet until the species is observed and recorded 
Fie. 54.—Hypoderma bo- we must consider its presence in America as merely 
vis: head of female fly g te = 
from the front—en. conjectural. The American Ox Warble, in every case 
larged (after Brauer). sq far observed, is the larva of Hypoderma lineata. 
This species has come to be known, especially through the South and 
Southwest, as the Heel Fly, on account of the habit which the female 
has of frequenting the legs of animals for pur- 
poses of oviposition. While the eggs are laid 
on other parts of the body that may be reached 
by the tongue, the species shows quite a strong 
tendency to select the flanks and legs around 
the heels, and the habit, almost everywhere ob- z 
served, that cattle have of seeking to protect yy. 55. Hypoderma bovis: a, 
their legs by running into water during the bot- _ puparium, from side; d, same, 
fly season finds its explanation in these facts. °™ 2bove, showing exit hole 
of adult; ¢c, cap which splits 
The eggs are attached firmly, by a strong cleft, of to anow the adult to issue— 
in rows of from five to ten or more, to the hairs. 2 #tural size (after Clark). 
When the cattle lick themselves, the young larve are taken into the 
mouth, as, under pressure and moisture, the egg readily splits at its 
anterior end and releases the young larva, which is already well de- 
veloped when the egg is laid. Doubtless quite frequently the eggs 
with the contained larve are taken with the hair in this licking, but in 
either event the larva in leaving the egg is armed with many minute 
Spines, which permit it to adhere to and to penetrate the walls of the 
esophagus. Here it soon molts and takes on the second of smooth 
stage, which for eight or nine months wanders slowly in the tissues of 
its host. The slow movement and the little nourishment taken reduce 
the inflammation and irritation to a minimum; in faet, the most re- 
markable thing in the life-history of this larva is the long period of la- 
tency and the slight development that takes place during the summer 
and autumn months. During the late winter the larva reaches a point 
beneath the skin in the region of the back and penetrates the skin, 
anal end first as Dr. Curtice believes, and as seems most probable. 
Here it molts a second time and reassumes its spinous character, pro- 
ducing more or less inflammation and developing rapidly with its en- 
larged spiracles fitted for more perfect breathing. The third molt soon 
follows, and we get the more strongly spined grub, with its still larger 
spiracles, which lives in the swellings or sacs so well known to stock- 
men. It finally works its way out, drops to the ground, which it enters, 
Rh ere 
