1916 ENTOMOLOGICAL SOCIETY. 117 



have to search a little further, probably, and gain more experience before wo 

 learn the actual cause of the terror in cattle and horses caused by the Bot and 

 Nose Flies. The contributions that have been made on this subject to-day are 

 of great importance and I wish to express the feeling of pleasure that I have 

 in meeting you all to-day and to assure you that my Branch will assist Dr. Hadwen 

 in carrying on the work he is now engaged in. 



The President: The Society is very much indebted to Dr. Torrance for his 

 valuable contril)ution and for the information which he has given from the vet- 

 erinary side. 



Dr. Torrance: Mr. President, I have brought up with me some specimens 

 and pictures which Dr. Hadwen sent me. 



The President: The question of the effects of internal parasites which Dr. 

 Torrance brought up is one which has been always of great interest to me, and it 

 becoming more generally realized that the importance of these parasites is not 

 so much because they are present but owing to the fact that their presence may 

 be responsible for the penetration of the mucous mertibrane of the alimentary 

 tract. Now these two papers have a number of important points and T have no 

 doubt there are other members who would wish to discuss them. 



;Mr. Totiiill: Mr. Chairman, this paper to me is one of the most interesting 

 that has been presented for some years on account of its extremely interestino^ 

 biological points and on account of its significance. It may he interesting to 

 recall that the origin of the Oestridse is quite uncertain, but at the same time 

 they are undoubtedly related to the parasitic dipterous families Tachinida^ and 

 Dexiidie. In my studies on life-histories of the Tachinidae some years ago it be- 

 came evident that there was something the matter wnth the supposed life-history 

 of the Bot Fly. In the Tachinidffi there are flies which deposit eggs which are 

 taken into the alimentary canal. The larvfe migrate from the alimentary canal 

 to various tissues of the host. In every known case in which this habit obtains 

 the egg is modified for passing down the alimentary canal without injury. In 

 the eggs of these w^arble flies it is evident that there is no such modification for 

 such a habit and this work of Dr. Hadwen's clearly shows that the larvrc do 

 not pass through the alimentary canal, is very interesting. 



Mr. Sanders: In regard to the date of introduction of Hypoderma hovis 

 into Canada, we have a pretty fair idea as to when it first became common in 

 Nova Scotia owing to the faot that oxen are worked so much more down there 

 than in the rest of Canada. Farmers will tell you that the Gad Fly became a 

 nuisance in Nova Scotia about fifteen years ago. It causes a little damage that 

 has not been mentioned in these papers, that is, the damage that the oxen do 

 wlien tliey are attacked by tbese insects. It drives the oxen almost frantic; appearing 

 about the 10th July and attacking the oxen all through haying time. Some- 

 times they will he driven so wild as t-o run away with the loaded hay waggons, 

 and often will break wheels, axles, tongues or yokes in their efforts to get away 

 from the insects. We find that cattle are mostly attacked in the open, and when 

 a Gad Fly appears in a herd of cattle they will at once take to the bush where 

 they seem to be free from attack. From Dr. Hadwen's work, can Mr. Treherne 

 suggest any method of control ? 



Mr. Treherne: I don't think it would be letting Dr. Hadwen's secrets out 

 if I told you that he is pretty well satisfied he can effectively control these flies. 

 Now that the penetration takes place through the skin, he thinks he can dip 

 every ten davs or so and give the larva? a dose of arsenic. 



