1916 ENTOMOLOGICAL SOCIETY. 103 



My reply led another Western reader to make a spirited reply to my statement 

 that the bot flies cannot sting either with its mouth-pa,rts or with its ovipositor. 

 He says: — 



My experience with " nose flies " that annoy horses dates iback eight years. 

 Previous to that time they were unknown in the district. A bunch of horses were 

 brought in from the United States the year before and from them I think we obtained 

 this pest. Of course we always had the long-tailed bot-fly, but this bob-tail is a curse 

 both to horses at work and in pasture. Work horses can be given some protection in 

 the shape of nose covering, but the poor horses outside cannot even feed in the day- 

 time for them. If you could see the poor beasts huddled up together stamping, rubbing, 

 etc., I am sure you would not think the laying of an egg by these pests so simple a 

 matter. Come and hitch up a six-horse outfit without any protection sometime this 

 coming summer and you will change your mind. Anyone who will take the trouble 

 to examine these bob-tail bot flies will notice on the tail end a pair of tweezers when 

 pressed slightly. It is from these tweezers the trouble arises. 



In my reply to correspondent 'No. 2 1 suggested that perhaps the real culprit 

 was a Tabanid for these insects are known as Gad-flies, Breeze-flies, Greenheads 

 and Ear-flies, but asked for specimens. Correspondent No. 2 was good enough 

 later to send a few specimens of the Nose flies and made further observations 

 regarding their habits: — 



These pests have been some weeks later making their appearance this year, owing 

 I presume to the late frosts. I think the description you once gave, namely, red- 

 tailed (bot-fly, was fairly accurate, but strange to say I have looked very closely for 

 their eggs but have failed to find any — so different from the ordinary long-tailed bot, 

 which distributes its eggs promiscuously. On squashing an ordinary bot fly one flnds 

 numberless eggs, but in these I have failed to see any. The habits of these nose flies 

 are to hover around a foot or so above the earth, when they make a dart upwards and 

 try to hit the horse on the lips or nostrils; it also seems to dig its hind part similar 

 to a bee or wasp when stinging an object. It rarely hits but once at a time, when it 

 seems to disappear for a few seconds, then comes again. I have examined its rear 

 end for stinging apparatus, but can only see what to me appears a pair of tweezers. 

 "We have all the other kinds of horse flies you mentioned, but a horse will calmly 

 endure being chewed up with the spotted winged horse flies, bull dogs and the rest of 

 that family, but let one of these nose flies strike and he Is up in the air at once and 

 has to rub his nose on something or other. As I mentioned in my previous letters it 

 is only a few years since they made their appearance in this district and I have heard 

 that there are parts of this province where they have not yet made their appearance. 

 They are the greatest pest we have got on horses. I think the Royal Humane Society 

 should get busy and make all owners provide some building In which any stock in 

 pasture could go in for protection. I have a pole and straw shed which I put up for 

 winter and the straw has settled down a little, which leaves an air current at the top 

 of walls. My stock appreciate it and it is also a protection from the bull dog flies, 

 too, which are a great annoyance to cattle as well as horses. These nose flies don't 

 touch cattle. 



My reply was as follows: — 



We were very glad to get four specimens of nose flies from Saskatchewan, for their 

 arrival sets at rest the question of the identity of the flies that bother the horses sa 

 much in the western provinces. They are nose flies (Oastrophiliis nasalis) , and are 

 one of the species of horse bot-flies. Now our friend S. H. differs from us on the power 

 of stinging these nose flies possess. We maintain that these flies do not and cannot 

 sting, for they have no stinging appliance. In all kinds of flies that sting the mouth- 

 parts are modifled to form a stinging or piercing apparatus; on the other hand, in all 

 the kinds of bees and wasps that sting the egg-depositor at one hind end of the body 

 is modified for piercing purposes. Now, as bot-flies are true flies we would naturally 

 expect their mouth-parts to show piercing appliances if they can really sting, but exam- 

 ination reveals no such appliances. Moreover, the egg-depositor at the hind end of the 

 body is rather long, but it is too soft and flexible to serve as a stinging instrument. 



If these ibot or nose flies cannot sting, why do they cause such panic among horses? 

 The answer is, we believe, the persistent efforts of the flies to deposit their eggs on 



