﻿THE CATTLE GKUBS OR OX WARBLES 107 



ment than would be supposed. On an average it required an hour 

 to treat about 98 grubs by the application of ointments, such as 

 iodoform-petrolatum to cysts in the backs of cattle. Undoubtedly 

 this work could be done much more rapidly in herds showing a 

 fairly heavy infestation. 



The cost of materials and equipment should be considered, espe- 

 cially if large herds are to be treated. The fact that no instru- 

 ments or materials are needed for the ordinary hand extraction 

 commends that method. With the use of ointments, powders, and 

 washes practically no equipment is required. The cost of forceps 

 or scissors for the puncturing and pulling method of extraction is 

 not great, but this method requires rather more care and a higher 

 degree of training for the work than is necessary for using the 

 oil-can injection method or for applying washes and powders. 



The cost of the chemicals used varies considerably with the ma- 

 terial, and there is also considerable difference between the whole- 

 sale and retail prices of each. Iodoform-petrolatum ointment costs 

 about 81/4 cents per ounce at the usual wholesale price. The retail 

 price is about 15 cents per ounce. An ounce will treat between 

 125 and 200 grubs, thus making the retail cost of the ointment about 

 12 cents per 100 grubs. Pj^rethrum ointment is much cheaper, 

 as it costs about 5 cents per 100 grubs. The only objection to this, 

 ointment is that the pyrethruni powder must be fresh to be potent. 



With such materials as carbon tetrachloride and benzol, it was 

 found that a pound of either would treat about 500 warbles. Since 

 these materials are comparatively inexpensive the cost is extremely 

 low. 



As yet derris is not available on the open market in this country, 

 but it is probable that it will retail at approximately $1 per pound. 

 Tobacco dusts of all grades are very much cheaper, but they do 

 not appear to be equally effective in any strength, and furthermore 

 their strength as well as mechanical make-up varies considerably. 

 It is probable that if further tests prove that very fine tobacco dust 

 with a fairly high percentage of nicotine is as effective as the writers' 

 preliminary experiments indicate, this material may be standard- 

 ized for this purpose. 



CONTROL THROUGH INDIVIDUAL EFFORT 



The results of control measures applied by an individual cattle 

 owner when he is more or less closely surrounded by livestock are 

 likely to be disappointing. Three tests have been made by the writers 

 in which the grubs have been destroyed rather systematically for 

 j>ei-iods of from two to four years. It is true that all grubs were not 

 destroyed each year, but the work was probably done as thoroughly 

 as it woukl have been if left to the cattle owners. The jmstures where 

 the treated cattki ranged wei-e in close proximity to others in which 

 untreated stock were kept. In none of these tests was a striking 

 reduction observed in the numl)er of grubs during the year f()lh)wing. 



The most thoi-ough work ahmg this line was done on the dairy 

 !infl breeding farm of J. T. Orr, near Dallas, Tex. From 45 to 100 

 head of cattle were carried on this place. During the grub season 

 of 1020-21 the cattle were examined and gnil)s destroyed only once, 

 on January 29. "^rhe average number of grubs per head then was 



