﻿THE CATTLE GEtJBS OR OX WAEBLES 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 th.e\ work. In 

 the present writers' expei'ience, however, washes have not been 

 found materially to facihtate 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 larvae 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 giTibs from the backs of cattle by suction. One of the prin- 

 cipal difficulties 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. Broclersen (11), 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 

 barrel 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 pmnp (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 ti-ying on the fmgere than hand extraction and the 

 operator would not have the disagi^eeable experience, which often 

 comes from sfjueezing the grubs out by hand, of having pus, or the 

 contents of the grub, squirted into the face. Furthermore, it is 

 prol)al>le that the chance of l^-eaking 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 larvse naturally 

 comes to mind. The writers have investigated the possibility of 

 using various types of forceps in this work. One of the pi'incipal 

 diflifiilties is in obtaining a pair of forceps with sufliciently fine 

 points to enter the sirjall liolcs in the hide, and at the same time 

 Avith enough strength to exti'act the hirvje and not get out of oi'dei'. 

 One of the most successful forms of forceps tried is the alligator-jaw 



