1908. The British Association in Dublin, 245 



S0:\IE IRISH EXPERIMKNTvS ON WARBLR -FLIES. 



BY PROF. GKO. H. CARPENTER, RSC, MR. I. A. 



For the past four years experiments have been carried on by the 

 Irish Department of Agriculture as to the life-history of the warble-flies 

 and the effect of the commonly accepted means for checking their 

 attacks on cattle. The experiments were, for the most part, carried on 

 at Balhhaise, Co. Cavan. 



In January of this year, a first report of these experiments was pub- 

 lished in the Department's lourual by the writer and Mr, J. W. Steen. 

 The most important practical result of the experiments has been to 

 show the uselessness of dressing cattle either with carbolic "dip," oil 

 and tar "smear," or paraffin emulsion with the object of preventing egg- 

 laying. 



For example, six yearlings were smeared all over every day from May 

 till September, 1906. In 1907 they showed warbles averaging over 30 

 per beast. Four calves sprayed all over daily during the same period 

 showed an average of 15 warbles per beast the next spring. The average 

 number of warbles on untreated animals at the same time was 31 for 

 heifers and it for calves. 



In the spring of 1907 a systematic squeezing-out and destruction of 

 maggots was set on foot : 2,000 maggots were obtained from 194 head of 

 cattle on the Ballyhaise farm, an average of nearly 11 per head. The 

 good effect of this operation has been strikingly shown in the spring of 

 the present year, when from 166 head of cattle only 694 maggots were 

 obtained — an average of 4'2. Equally instructive is the fact that five 

 cows grazed on the ovitskirts of the farm, and therefore open to the 

 attacks of flies from the surrounding country, had an average of 16 

 warbles per beast, while 94 cows grazed near the centre of the farm had 

 an average of only 3 warbles per beast. Observations show that the flies 

 lay their eggs usually on the legs, very rarely on the backs of cattle. 

 During the summer of 1906 six calves were muzzled by day and tied up 

 between stakes at night, so as to prevent them from licking themselves. 

 All but one of these had warbles in the spring of 1907, whence it was sur- 

 mised that the maggots ma}- gain entrance through the skin, and not, 

 as is now generally believed to be the case, through the mouth. During 

 the summer of 1907 two calves were muzzled and tied, with additional 

 precautions. These were the only two calves on the farm that as year- 

 lings are entirely free from warbles this spring (1908). It is likely, 

 therefore, that the protection from licking in the 1906 experiments was 

 in some way incomplete. During the present summer six calves are 

 being again treated in this way, and it is hoped that the method of 

 entrance by the mouth will thus be conclusively tested. 



Hypoderma bovis seems to be far commoner in Ireland than H. lineata. 

 In both species the interval between the emergence of the maggot from 

 the beast's skin and the appearance of the fly is about seven weeks. 



