108 THE EEPOET OF THE Is^o. 36 



cc. Posterior cross-vein opposite and nearer tTian the anterior cross-vein. G. nasalis 



(nose fly). 

 aa. Costal vein ends at tip of Ml-(-2; Ml-j-2 with a bend; cell R5 much narrowed 



or closed. 



b. Facial grooves approximated below; cell R5 closed and petiolate. Oestrus. 

 bb. Facial grooves far apart; squamae large, ovipositor elonga;te. Hypoderma. 



c. Prothoracic band of yellow hairs, mesothoracic band of brownish black hairs; 



media 3 sinuate; legs black with black hair; tips of hind tibiae and tarsi 

 yellowish brown. H. bovis. 

 cc. Thoracic band of hairs brownish; media 3 rounded; tibiae and tarsi yellow; 

 femora black. H. lineata. 



The President: We are pleased to have Professor Lochhead's paper in our 

 Proceedino-s, because this is a group of insects which is gradually coming to the 

 front more and more. It is very apparent that, both in the case of the Nose 

 Flies attacking horses and in the case of the Warble Flies attacking cattle, these 

 insects are hecoming far more frequent. Our own correspondence files would 

 display a somewhat similar series of letters as Professor Lochhead has read here, 

 and the. farmers who write to usi about these things are very confident about 

 their own observations and their own knowledge, as a rule. In regard to a ])rief 

 note that Professor Lochhead mentioned about warble flies, I believe wdiat he 

 says is quite true, that we can trace the increasing prevalence of Hypoderma hovis 

 in this country to the importation of cattle. In the old days the only species 

 recognized in this country was Hypoderma lineata, which was considered to be a 

 truly native species, but more recently, owing to the investigations of Dr. Hadwen 

 in British Columbia and my o^vn enquiries from the Branch here, w^e were able 

 to show that hovis occurred in this country in addition to lineata, and further 

 that hovis was pretty widely distributed, particularly in the Province of Quebec, 

 and it is on this suspicion that Dr. Hadwen has based most of his very valuable 

 inyestigations, but before passing on to this paper I think there are a number 

 of points in Professor Lochhead's paper which might be discussed. We might 

 discuss the two papers together. 



Prof. Lochhead: Since the two papers deal with almost the same subject, 

 I think it would be preferahle to have the discussion on the two papers at the 

 same time. 



Dr. Hewitt : We shall now have Dr. Hadwen's paper entitled " Further Notes 

 on the Warble Fly, Hypoderma hovis." 

 Eead bv Mr. Treherne. 



THE SEASONAL PKEVALENCE OF HYPODERMA BOVIS TN 1915, 



TOGETHEE WITH OBSEEVATIONS ON THE TEEEIFYING 



EFFECT H. BOVIS HAS UPON CATTLE, AND 



LESIONS PEODHCED BY THE LAEVA. 



Seymour Hadwen, D.V.Soi., Agassiz, B.C.- 



The observations and experiments on H. hovis which were conducted at 

 As-assiz this year, are all preparatory to the work which is contemplated for next 

 veRr, on the prevention of egs; laying and destruction of larvae. 



A previous paper has been written on the seasoned prevalence of H. lineatum.. 

 It is remarkable that so little is known about the seasonal activity of these flies, 



