1916 ENTOMOLOGICAL SOCIETY. 115 



are running when the fly is laying, so that the eggs are deposited at random. 

 On a number of occasions H. bovis was seen flying beside the animals just about 

 level with the stifle joint, striking repeatedly at the outside of the leg. This is, 

 I find, the most common manner of ovipositing during rapid flight. Another 

 favorite way. is to follow a foot or two behind, then catching up and striking 

 just below the pin bones. But the flrst few strikes prior to the animals getting 

 away are almost invariably on the legs, lower down. 



Summary. 



The seasonal activity of H. hovis at Agassiz is from the beginning of June 

 to the beginning of August, 



The last larvas to emerge from the backs of cattle, leave during the first 

 days of July, 



In H. bovis the pupal period averages thirty-five days. 



High temperatures shorten the pupal period. 



The fear cattle have for H. bovis is due to the insect's persistence and manner 

 of egg-laying, 



Hewitt's observations on the penetration of the skin by the larvae of H. bovis 

 are confirmed. 



The lesions caused by the larvse, differ from those of H. Ivneatum. Older 

 animals show more lesions than the young. 



References. 



Carpenter, G. H,, Hewitt, T, E., Reddin, T, K, 1914. The Warble-flies. 

 Fourth Report on Experiments and Observations as to Life History and Treat- 

 ment. Jour, Dept. Agr, and Tech, Instr, Ireland, Vol. 15, No. 1, pp, 105-132. 



Hadwen, S, 1912, Warble-flies; the Economic Aspect and a Contribution 

 on the Biology. Dept, Agr. Canada, Health of Animals Branch. Bulletin 16. 



Hadwen, S. 1915. Warble-flies; a further Contribution on the Biology of 

 H. lineatum and H. bovis. Parasitology (Camb). Vol. 7, No. 4, Mar. 19, 1915. 



Lucet, A. 1914, Recherches sur revolution de VHypoderma bovis (deGeer) 

 et les moyens de le detruire, Comptes Rendus de L'Academie des Sciences. 

 Tome 158, No, 11, Mar, 16, 1914. 



Note.— I am indebted to Dr. F. Torrance, Veterinary Director-General, for permis- 

 sion to publish this article. 



The President : Mr, Treherne is to be congratulated on the excellent manner 

 in which he has presented another man's piece of work. It is very difficult 

 to present in so intimate a manner the work which another man has been res- 

 ponsible for, but it shows how closely Mr, Treherne has watched and been interested 

 in the work of Dr. Hadwen, I think it is one of the most important papers 

 that has been discussed at this meeting. The question of the method of entrance 

 of Hypoderma bovis has been a disputed point for many years and we have had 

 observations and evidence supporting now one view and now another, but in 

 view of Dr. Hadwen's conclusive experiments, which have been supported by 

 photographs, I think he has cleared up this question. We are pleased to have 

 with us this morning Dr. T, Torrance, the Veterinary Director General of the 

 Health of Animals Branch, Department of Agriculture, and perhaps lie would have 

 something to say in connection with these two papers. 



