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XIX. 



THE REPRODUCTIVE ORGANS AND THE NEWLY HATCHED 

 LARVA OF THE WARBLE-FLY (HYPODERMA). 



By GEORGE H. CARPENTER, B.Sc, M.RI.A., 

 Professor of Zoology in the Royal College of Science, Dublin ; 



AND 



THOMAS R. HEWITT, A.R.C.Sc.L, 

 Research Student in the College. 



(Plates XXI-XXVI.) 



[Read February 24. Published Apbil 29, 1914.] 



For nearly ten years past observations and experiments designed to complete 

 our knowledge of the life-history of the Warble-fly — of which there are in 

 Ireland as in Great Britain and on the Continent two species : Hypodevma 

 bovis (De Geer) and H. Uneatum (Villers) — have been carried on at Ballyhaise 

 Agricultural Station, in Co. Cavan, under the auspices of the Department 

 of Agriculture and Technical Instruction for Ireland. Attempts have also 

 been made to ascertain the most effective means for exterminating these 

 destructive insects, or at least of considerably reducing their numbers. Three 

 reports containing the results of several years' work have already been 

 published (Carpenter, and others, '08, '09, '10). During 1913 these researches 

 have been continued on an extended scale of operation, and one of us 

 (T. R. H.) has had the opportunity of spending the whole summer on the 

 farm at Ballyhaise, so as to study the insects in their various stages, and to 

 watch tlie effect of the flies and their egg-laying on the cattle. It is 

 remarkable that the problem of the Warble-fly is being simultaneously attacked 

 in several countries at the present time ; we would call attention to the recent 

 publications of Hadwen ('12) and Glaser ('13), who are working respectively 

 in Canada and in German}^ on lines very similar to our own. 



The mode of life of the stages of the Hypoderma larvce within the bodies 

 of cattle has long been known ; the behaviour of the larvae hatched from 

 the eggs laid on the beasts' hairs, and tlie mode of their entrance into the 

 host's body, are the points still requiring investigation. According to one 

 view the young maggot must bore through the skin. According to other§ 



