224 SHEEP GAD-FLY. 
be dislodged and removed by a feather dipped in oil of tur- 
pentine, or a weak solution of carbolic acid, or of creosote. 
Salt water or diluted carbolic acid solution, injected with a 
syringe, does good service. Finely powdered lime is also 
used to cause violent sneezing, thus dislodging the larve. 
Some stock breeders smear the noses of their sheep with tar, 
or force them to do so themselves by attracting the animal 
to large auger-holes in logs baited with salt, and by coating 
the rims with tar; still others provide in the yards dry 
places covered with deep dust, into which the animals can 
thrust their noses if pursued by their tormenters. Ina few 

Fig. 182.—Three larvz of sheep gad-flies in frontal sinuses of sheep. Enlarged. Orig. 
cases the writer had an opportunity to use pyrethrum or 
Persian insect-powder. This material was blown forcibly 
into the nostrils of the sheep, and dislodged a number of the 
worms. It can also be used as an extract in alcohol, and 
will no doubt be very effective, as most dipterous larve are 
very sensitive in regard to this substance. 
The illustration (fig. 180) shows the different stages of 
this insect, and fig. 182 three larve in the frontal sinuses of 
a sheep. 
There are a large number of bot-flies which exist in tum- 
ors they themselves have caused. The genus Hypoderma 
especially contains species that infest domesticated animals, 
hence these are best known; yet how little is really known 
about these parasites is indicated by the fact that until 
quite recently it was thought that the young larve forced 
