29. The gadfly, bot-fly,
or sheep-fly: the larva lives in the bodies of cattle
throughout the whole winter; it is extracted from their backs
by an African bird called Buphaga. Adhering to the anus it
artfully introduces itself into the intestines of horses, and
becomes so numerous in their stomachs, as sometimes to
destroy them; it climbs into the nostrils of sheep and
calves, and producing a nest of young in a transparent
hydatide in the frontal sinus, occasions the vertigo or turn
of those animals. In Lapland it so attacks the rein deer that
the natives annually travel with the herds from the woods to
the mountains. Lin. Syst. Nat.]

[Footnote: _The wing'd Ichneumon_, l. 33. Linneus describes
seventy-seven species of the ichneumon fly, some of which
have a sting as long and some twice as long as their bodies.
Many of them insert their eggs into various caterpillars,
which when they are hatched seem for a time to prey on the
reservoir of silk in the backs of those animals designed for
their own use to spin a cord to support them, or a bag to
contain them, while they change from their larva form to a
butterfly; as I have seen in above fifty
cabbage-caterpillars. The ichneumon larva then makes its way
out of the caterpillar, and spins itself a small cocoon like
a silk worm; these cocoons are about the size of a small
pin's head, and I have seen about ten of them on each cabbage
caterpillar, which soon dies after their exclusion.

Other species of ichneumon insert their eggs into the aphis,
and into the larva of the aphidivorous fly: others into the
bedeguar of rose trees, and the gall-nuts of oaks; whence
those excrescences seem to be produced, as well as the
hydatides in the frontal sinus of sheep and calves by the
stimulus of the larvae deposited in them.]

[Footnote: _While fierce Libellula_, l. 37. The Libellula or
Dragon-fly is said to be a most voracious animal; Linneus
says in their perfect state they are the hawks to naked
winged flies; in their larva state they run beneath the
water, and are the cruel crocodiles of aquatic insects. Syst.
Nat.]

[Footnote: _Contending bee