374 PESTS OF DOMESTIC ANIMALS 
The Screw-worm (Chrysomyia macellaria Fab.) 
Exposed wounds or even the bites of ticks form the breeding ground 
of the whitish maggots of this species. Eggs are laid in large numbers 
in such places by the adult fly, 
and the young burrow in the 
surrounding tissues, later enter- 
ing the ground to transform. 
There may be several genera- 
tions annually. 
Prompt treatment of chance 
wounds, and dipping to kill or 
prevent ticks, are the best 
Fic. 599. — The Screw-worm Fly. En- measures to adopt. In the 
larged and natural size. Original. 
treatment of wounds a solution 
of carbolic acid, 1 part, water, 30 parts, is excellent, followed by a 
dressing of pine tar. 
Sucking Lice on Domestic Animals 
The larger animals, including cattle, horses, swine, and others, 
are often infested with sucking lice, which frequently cause great 
irritation. Several species are common. 
The Short-nosed Ox Louse (Hemato- 
pinus eurysternus Nitzsch) is slaty in 
color, one eighth to one fifth of an inch 
long and about half as broad. Usually it 
is most troublesome on the neck and 
shoulders. 
The Long-nosed Ox Louse (Hematopinus 
vituli Linn.) is slender, one eighth of an 
inch long. Its head is distinctly elongated. 
The Hog Louse (Hematopinus urius 
Nitzsch) is gray, one fourth of an inch 
long, the body broadly elliptical, the 
head narrow. Badly infested pigs fail to 
make proper gains in weight. 
Fic. 600.— The Short-nosed 
Ox Louse. Enlarged and 
natural size. Original. 
