THE CATTLE GRUBS OR OX,WARBLES 7 109 
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 1s constantly amen- 
able to treatments applied to the backs of the cattle or to extraction. 
3. The larve are present in the subcutaneous tissues of the back 
during a fairly well-defined and comparatively limited period of the 
ear. 
The difficulty of carrying out systematic extraction or the apph- 
eation 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 
futility 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, 
the 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 known 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 werk 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 thought best to have all of the work of 
destroying the grubs carried out by men specially trained in the pro- 
cedure, and not to depend upon the volunteer efforts of the stock 
owners. It is probable that such an undertaking would have to be 
carried on during about three years, as inevitably a few grubs would 
escape destruction even in the most carefully executed plan. It ap- 
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