92 BULLETIN 1369, U. 8S. DEPARTMENT OF AGRICULTURE 
most cases applied with the fingers, care being taken to press some 
of the material into the apertures in the skin (fig. 34). The liquids 
were applied with hypodermic syringes, a blunt needle being used 
and care being taken not to injure the grub; with oil cans (fig. 35) ; 
with eye droppers; or in the form of a general wash thoroughly ap- 
plied to the backs of the cattle with a stiff brush. In preliminary 
tests with all of the materials the cattle were numbered and a dia- 
gram made of the distribution of the grubs on the back, each grub 
being numbered and the stage of development determined before 
the application was made. In some instances the hair was clipped 
from around the openings in the hide; but the results in each case 
were checked afterwards by the treatment of other infestations in 
Fig. 34.—Applying ointment to grubs in back of heifer 
which the hair was left undisturbed immediately around the holes 
and the position of the grubs marked by clipping the hair below each 
of them. In injecting the materials into the cysts an effort was made 
to fill the cavity around the erub with the liquid. The average 
quantity used was something less than 1 cubic centimeter per grub. 
In order to determine the results of the treatment in the early experi- 
ment, each grub was carefully examined from four to six days after 
the treatment was made. Then the larvee were extracted and notes 
made on their condition and the condition of the lesions produced by 
them. Following the preliminary tests, large numbers of grubs were 
treated without determining the stage they were in or otherwise in- 
terfering with them before the application. The percentage of mor- 
tality in some cases was determined merely by continued observation 
