332 The Diseases of Animals 
the thorax. The adult fly deposits its eggs on the sur- 
face of a wound. They hatch within a few hours, the 
larve (maggots) burrowing their way into the tissues, 
where they remain for about a week. Then they escape 
to the ground, pupate, and soon change into adult flies. 
In some regions the secrew-worms are a great pest, 
and cause serious loss to live stock. They attack an 
animal in even the smallest wound, such as the pune- 
tures made by ticks, wire cuts, brands, and the like. 
The treatment recommended by Dr. Francis, of 
Texas, is to use pure ereolin, or similar coal-tar prod- 
uet, in a machinist’s oil-can, squirting it thoroughly into 
the wound. Oilof tar is also good. Fresh wounds can 
be protected by covering with tar. 
THE HORN-FLY 
The horn-fly is a small insect (Hematobia serrata) 
about half the size of the common house-fly, and of the 
same general shape. It was imported into America about 
1887, and has spread over the whole country. It is a 
European insect. It causes considerable irritation to 
eattle, and a consequent loss of milk and flesh. The 
name comes from the fact that these flies collect in 
large numbers at the base of the horn to rest. They 
do not bother cattle when in this position, but bite 
them on the skin of the back, sides and flank. 
Apply some substance to the surface of the animal’s 
body to keep the flies away. A mixture of equal parts 
of pine-tar, kerosene and fish-oil is excellent. The tar 
is first “eut” by the kerosene, then the fish-oil is added. 
