THE CATTLE GRUBS OR OX WARBLES 101 
the cyst and allow the larva to escape. Certain writers have advo- 
cated the application of salt water or soapy water to the backs of 
cattle before extraction is begun. It is probable in the case of cattle 
with elastic skins that a weak saline solution applied to the backs 
some time before extraction is undertaken will aid the work. In 
the present writers’ experience, however, washes have not been 
found materially to facilitate extraction. (See further discussion 
under “ Cost of treatment or extraction of grubs,” p. 106.) 
MECHANICAL EXTRACTION OF GRUBS 
One often hears of the old-fashioned method of placing the mouth 
of a heated bottle over the aperture of the grub.. Some larve may 
be extracted by this method, but it is extremely slow. It suggests, 
however, the possibility of utilizing suction and pressure in extrac- 
tion work. For several years the writers have given considerable 
attention to the question of developing an implement for remov- 
ing the grubs from the backs of cattle by suction. One of the prin- 
cipal Geultias encountered is in obtaining an airtight cup to fit 
over the warble and to generate, without unduly complicated and 
expensive apparatus, a sufficient vacuum to suck the grubs out of 
the cysts. Brodersen (//), a veterinarian in Denmark, has devised 
and patented a small suction pump operated by hand which he con- 
siders a success for the removal of grubs. The principle employed 
is a combination of pressure and suction. The end of the pump 
barre] is fitted with a rubber cup which is applied to the back of 
the animal over the grub hole. This is pressed down, against the 
animal while the plunger is being pulled out, thus creating a par- 
tial vacuum. Doctor Brodersen has very kindly furnished the writ- 
ers with one of these instruments, but in their experiments it has 
not worked well, especially on animals with inelastic skins. In cer- 
tain instances, even though tremendous pressure was applied and 
the plunger raised a great. many times, the grubs could not be pulled 
out of their cysts. Before receiving Brodersen’s extractor, the 
writers had developed a similar instrument made from an old au- 
tomobile-tire pump (fig. 37). This, probably owing to a larger 
barrel capacity, gave even better results than the imported extractor. 
There is certainly some advantage in using’ an instrument. of this 
kind if it can be developed to a point where a large percentage of 
the grubs can be removed without consuming too much time. It 
would be less trying on the fingers than hand extraction and the 
operator would not have the disagreeable experience, which often 
comes from squeezing the grubs out by hand, of having pus, or the 
contents of the grub, squirted into the face. Furthermore, it is 
probable that the chance of breaking the cysts or bruising the tis- 
sues would be less than might result from hand extraction, espe- 
cially by an inexperienced operator. 
The use of forceps to assist in the extraction of larve naturally 
comes to mind. The writers have investigated the possibility of 
using various types of forceps in this work. One of the principal 
difficulties is in obtaining a pair of forceps with sufficiently fine 
points to enter the small holes in the hide and at the same time 
with enough strength to extract the larve and not get out of order. 
One of the most successfui forms of forceps tried is the alligator-jaw 
