AMERICAN OX WARBLE FLY. 137 
from abroad, a very large proportion are badly warbled. ‘There is 
also great difficulty at times by introduction of warble on Ivish cattle 
into farmsteads, where the greatest care is being exercised to keep 
the cattle free of infestation.”” I have once myself had imported 
American warble sent me. This kind—the Hypoderma lineata—has 
long been known to be in Britain, and the infestation may be found 
together with that of the maggots of our own kind—the Hypoderma 
bovis—even on the same beasts; but I am not aware of anything that 
can be considered prevalence of this species.* 
From the collective testimony given above, it seems to me to be 
proved that a spring clearing cannot be looked to as a means of 
‘stamping out” warble; but at the same time there is no doubt, that 
is to say, we hold the proofs in our hand from twelve years’ minutely 
recorded work over a large district, that very great benefit is caused 
where the spring destruction of the maggots is properly carried out. 
We have plenty of trustworthy records of benefit from squeezing 
out or otherwise destroying the maggots, and also of benefit of pre- 
vention of attack by use of washes or dressings to keep the fly from 
ego-laying in summer; but I am not aware of our possessing any 
other record than that given below of the work being carried on 
persistently in the spring season of twelve successive years, that is, 
from 1885 to the spring of 1897 inclusive, and on an area where, 
taking the table for 1888 as an example, the cattle on the twenty-three 
steadings under operation, besides the few animals of cottage owners, 
included three herds of 25 to 27 cows; four herds of 82 to 40 cattle ; 
one of 50, and one of 56; and four others respectively of 57, 72, 79, 
and 86 animals, chiefly cows, but with a small proportion of heifers 
and calves. 
The work was begun in the year 1885 by Mr. W. Bailey, head- 
master of the Aldersey Grammar School, at Bunbury, Tarporley, 
* For much that is of interest regarding the warble of North America, see 
“The Ox Bot in the United States; Habits and Natural History of Hypoderma 
lineata,” by C. V. Riley; ‘Insect Life’ (United States Department of Agriculture), 
vol. iv. pp. 302-317. From these observations it appears that the American Ox 
Warble is a distinct species to ours, which is stated in this paper (published in 
1892), so far as was then known, not to occur in North America. The American 
writer considers there is a very important difference in early habits; the larva of 
their species commencing its progress from the gullet, and thence penetrating 
through the tissues, until after eight or nine months of this existence it reaches 
the back, and penetrates the skin, and forms a warble swelling, as is the case with 
our kind, the H. bovis. We have the H. lineata in this country, but with my best 
endeavours I have never been able to get specimens showing the attack in the 
cesophagus, or the larve in transit. For details of differences observable on careful 
investigation between these two species of flies, and also the differences between 
their larve, the reader is referred to the above paper, which is very fully 
illustrated. 
