GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 43 
flow of repellent, which was regulated by a stopcock, moistened a 
padded plank by means of a small pipe perforated with holes. This 
was placed at a salting and resting place of the horses and the amount 
of rubbing noted was very encouraging. Unfortunately, the horses 
did not rub the corners of the mouth, which are favorable places of 
egg deposition, and the scheme was abandoned. 
Dr. Van Es suggested the use of a repellent upon the forelegs of 
horses and other portions of the body accessible to the mouth, so 
as to cause the common bot fly to deposit eggs upon places where they 
could not be reached by the horse’s mouth. A marked repellent 
quality was observed in equal parts of pine tar and lard, no adults 
having been observed to oviposit during the following 4 days. There 
was apparently no injury to the animal, and 1 part of tar to 2 parts of 
lard was effective during 3 days. The disadvantage in some of the treat- 
ments was the fact that animals would walk through mud and water 
and cause a decrease in the repellent qualities of the mixture applied. 
Very good results were obtained with pine tar 3? ounces, kerosene 
4 ounces, laundry soap 1 ounce, powdered resin 1 ounce, and hot wa- 
ter to make 14 ounces. The pine tar was thinned with kerosene, the 
soap and resin dissolved in hot water, and the two mixtures poured 
together. There was not only great repellent action observed, but 
the resin caused the hair to stick together in small bunches and pre- 
vented the adult flies from ovipositing. There was apparently no 
injury to the skin of the animal, and these same repellents pre- 
vented G. nasalis from ovipositing under thejaws. A successful repel- 
lent that would not require renewal over a reasonable period is de- 
sirable, since the loss of time due to the renewal of repellents is a 
great loss. 
MECHANICAL PROTECTIVE DEVICES FOR WORK HORSES. 
The protective devices found upon work animals vary, but there 
are none used in the Dakotas on pastured animals. (See Plate V.) 
Various forms of fringes are most frequently found and may consist 
of leather, burlap, or a portion of the leg of trousers. These are 
probably the least effective of the devices, as examination of teams 
wearing such fringes developed the fact that they are often found 
infested with eggs. Leather seems to be the most efficient of the 
fringes, as it is not so easily blown aside by the wind and does not 
hinder the horses in breathing. Those extending completely around 
the head retail for 50 cents each, while those covering only the face 
sell for 25 cents. 
Baskets which are used extensively in nose-fly districts serve as 
muzzles during the last plowing of corn, but are not very effective 
nose-fly protectors. The mesh is of sufficient coarseness to permit 
files to oviposit if the lips can be touched. They do not always fit 
well at the top and occasionally a nose fly will get on the inside, 
