INTERNAL PARASITES 373 
A hole is made through the skin by which the grub gets air. These 
holes are a source of great loss in dressed hides, and the presence of the 
grub causes irritation and often loss of weight or of milk flow in the 
infested animal. 
The adult is about the size and shape of a honey-bee, but has only 
two wings instead of four. The sides of its head and thorax are marked 
with white, and on the upper surface of the thorax are four shining 
raised lines. The base of the abdomen is whitish. 
Eggs are laid in early summer attached to hairs near the heels of the 
animal. The egg opens as the animal licks its heels, and the young 
grub is carried by the tongue to the 
mouth. It at once penetrates the 
walls of the throat and for several 
months is in the connective tissue 
along the back of the neck and else- 
where. JT inally it settles under the 
skin of the back, and makes its breath- 
ing hole through the hide. When 
mature, it drops to the ground, where Warble. 
Fic. 598.—Larva of the Ox 
Original. 
it remains until the next spring. 
The presence of the grub results in damage to the beef, giving it a 
slimy appearance. In addition the hide is injured. 
Flies will not lay eggs on animals that are standing in water. In 
small herds strong-smelling oils may be smeared on the lower part 
of the legs, and will act as deterrents. A mixture sometimes recom- 
mended consists of sulphur, 4 ounces; spirits of tar, 1 gill; train oil 
(whale oil), 1 quart. As a rule the adult flies do not enter stables 
or attack animals under shelter. 
The grubs under the skin are best removed by pressing each side 
of the hole until the end of the grub protrudes, and drawing it out with 
tweezers. 
The best time to do this is in February or March. The grubs can 
be located by passing the hand along the back. If the grubs are thus 
removed, the flesh beneath will heal and the hole will close within a 
short time. 
