ORDER XII. DIPTERA.—THE BOT-FLY. 343 
the last segment elongated, flat, elevated, and terminated by four hairy ten- 
tacles ; at the sides of the fifth segment may be observed a little angle, from 
which projects a horny, retractile point. 
It is of very singular habits. It makes a small tunnel in the sand, having 
a conical mouth, where it waits, like the spider, immovable. As soon 
as an insect falls into the hole, it raises its head, and, squeezing its prey in 
the folds of its body, devours it, and afterwards throws out the skin. It 
lives in this way for at least three years before attaining the perfect state. 
Vorucetia. — The Volucelle have a strong resemblance to the bumble 
bee. Certain kinds make use of and abuse this resemblance to introduce 
themselves fraudulently into its nests, and to deposit their eggs therein. 
When these eggs have hatched, the larvw, which have the mouth armed 
with two mandibles, devour the larvie of their hosts (the bees), which is the 
return they make for the hospitality they have received. 
(estrus. — The Bot-Fly. In the whole insect world there is not a crea- 
ture so mischievous as this. It is the curse of the ox, horse, sheep, deer, 
and other animals during the summer. These creatures have an instinctive 
consciousness of its approach and sinister designs, and exhibit much rest- 
lessness and alarm. 
@. Ovis. — This species deposits its eggs in the nostrils of sheep, where 
the larva is hatched, and immediately ascends into the frontal sinuses, at- 
taching itself very firmly to the living membrane by two strong hooks situ- 
ated at its mouth. 
@, Bovis. — This species deposits its eggs in the skin of young beeves. 
They are soon hatched, and the larva, or worm, pierces the skin, making a 
considerable hole therein, which it makes its temporary dwelling-place. 
The back of the afflicted animal becomes covered with lumps, like tumors, 
or boils, which are filled with a purulent matter, upon which the larve feed. 
When their probation in this strange abode is completed, they creep out, fall 
to the earth, and make their way into the ground from one to two feet. 
@. Equi. — The Bot Fly of the horse deposits its eggs upon such parts of 
the skin as are liable to be much licked by the animal, and thus they are 
conveyed to the stomach, where the heat speedily hatches the larve, which 
are so well known as Bot-worms. After fulfilling their destiny here, they 
pass out with the excrement, and undergo their other change in the air. 
Although they are not always hurtful to horses, they sometimes prove 
fatal. 
These insects, in their perfect state, are not often seen, as they take no 
nourishment, and as soon as they deposit their eggs die. 
- Conors. —In this group the insects have the antenna much longer than 
the head, and the last two joints form a mass, with a terminal style. 
