﻿THE CATTLE GRUBS OR OX WARBLES 109 



2. Every individual of both species of Hypoderma is present in 

 the subcutaneous tissues of the backs of the cattle for a period in 

 excess of 35 days, and while in this situation it is constantly amen- 

 able to treatments applied to the backs of the cattle or to extraction. 



3. The larvse are present in the subcutaneous tissues of the back 

 during a fairly well-defined and comparatively limited period of the 



The difficulty of carrying out systematic extraction or the appli- 

 cation of ointments or washes under range conditions is at once 

 apparent. In the farming and dairying sections, however, where 

 the cattle are fairly gentle, systematic treatment would be fully 

 warranted even under present conditions. 



No definite experiments have been possible to show the distance 

 the flies may travel, but circumstantial evidence indicates that they 

 do not go far from the place where they hatch out, and this lends 

 further encouragement to the efforts toward control. The writers' 

 experience with the systematic destruction of grubs among animals 

 on a single farm surrounded by infested cattle clearly indicates the 

 futilit}^ of the individual attempting to secure a high degree of con- 

 trol, to say nothing of eradication. Cooperative community action 

 is therefore clearly called for. Such an undertaking in Denmark is 

 reported by Boas (5). On a farm in the center of an area where 

 systematic grub extraction was carried out by a dairy association, 

 tlie following numbers of grubs were found present and destroyed 

 on seven succeeding years, beginning in 1889: 832, 215, 65, 229, 64, 

 0, 0. Complete eradication was not accomplished toward the edges 

 of the areas covered by this effort, but the grubs were greatly 

 reduced in numbers. 



The stock raiser who has comparatively few grubs in his cattle 

 has not been given sufficient consideration in connection with the 

 sale of his cattle or hides, owing to the fact that it is the custom of 

 the hide buyers of a section loiown to be infested by grubs to make 

 a horizontal discount for grubbiness without determining the degree 

 of infestation of the hides and even without the knowledge of the 

 producer. With the inauguration of systematic control work there 

 seems to be little doubt that hide buyers would pay a premium for 

 hides from areas practicing control work, and also that butchers 

 would slightly favor cattle from those areas. 



In the initial undertaking of systematic control or eradication 

 work it would seem desirable that the plan be attempted on a con- 

 siderable area. Such a plan has been under consideration by the 

 writers for several years, although funds have not been forthcoming 

 to put it into effect (70). The writers believe that a large amount 

 of educational work must be done in advance of any actual control 

 work, and in this connection all organizations of business men and 

 farmers should be thoroughly in sympathy with the undertaking. 

 In an initial attempt it is tliouglit best to have all of the work of 

 destroying the grubs carried out by men specially trained in (he pro- 

 cedure, and not to depend upon the volunteei- efforts of (he stock 

 owners. It is probable that such an undei'taking would have to be 

 carried on during about thi-ee years, as inevitably a few gi'ubs Avould 

 escape destruction even in the most carefully executed plan. It ap- 



