kets. The risk of poisoning with tar mixtures as already mentioned
should be borne in mind in using this remedy. Care should be taken to apply
it lightly.

The stable fly breeds in moist accumulations of straw, chaff, cow or horse
manure, and various fermenting vegetable substances. The debris collecting
in and under outdoor feed troughs, and the remains of straw stacks are
favorable breeding places for the stable fly. Under the most favorable
conditions about three weeks are required for development from the egg to
the adult stage.

The proper care of straw and the proper disposal of stable manure are very
necessary in the control of stable flies. Straw stacks should be carefully
built so as to shed rain, and loose straw or chaff should be scattered or
burned. Straw not required for winter feed should be promptly disposed of
by burning or scattering and plowing it under. Stable manure should be
hauled out and scattered at regular intervals, preferably every three days,
and the vicinity of stables should be kept free from accumulations of straw
and hay that may become wet and serve as breeding places for the stable
fly.

THE HORNFLY (LYPEROSIA IRRITANS).[14]

This fly, now found nearly everywhere in the United States, was introduced
into this country from Europe about the year 1885. Hornflies have the habit
of clustering about the base of the horn (fig. 2), whence the name by which
they are popularly known. They do not damage the horn, and congregate there
only to rest.

In view of the general practice of dehorning cattle, the name hornfly is
less distinctive than it once was. Moreover, hornflies rest on other parts
of the body as well as the horns.

When resting, their wings are held down close to the body (fig. 1); when
feeding, their wings are held out nearly at right angles, ready for flight.
They puncture the skin and suck blood, usually attacking the upper parts of
the body, particularly those which are out of reach of the animal's head or
tail. Unlike most flies, they remain on the animal more or less constantly,
day and night. Owing probably to the irritation and annoyance caused by
these flies, cattle often do not thrive as they should during seasons when
the flies are numerous. The hornfly has also been charged with transmitting
diseases, such as anthrax.

[Illustration: PLATE XLIV. NORMAL SPLEEN AND SPLEEN AFFECTED BY
TEXAS FEVER.
Fig. 1. SPLEEN OF AN ACUTE, FAT