( Ivii ) 



clevei" detective stories, has told a tale of how a most marvel- 

 lous lady prevented a horse from wiuniiig the Derby (I am 

 writing from memory only) by letting loose some Tsetse flies 

 into the horse's box shortly before the race and thereby getting 

 the horse bitten and incapacitated through the Tsetse disease, 

 and his wonderful detective detected the fly on a man's arm in 

 the box and unravelled the crime : the idea is a most ingenious 

 one, but as a Dipterist I put it down at once as impossible. 

 Firstly, it is now known that the Tsetse fly, as a fly, commu- 

 nicates no disease, but, just as has been recently proved in 

 regard to malaria, it is only a contaminated fly that can con- 

 taminate a horse. Secondly, I do not think that three persons 

 could be found in Europe who could identify a Tsetse fly at 

 sight, and I strongly doubt if one could be found who would 

 recognise it alive and at liberty ; personally I know the Tsetse fly 

 very well in a collection, as I also know very well our common 

 Stomoxys calcitrans both in a collection and when flying about, 

 but I do not think that I should notice the dift'erence between 

 the species when seeing a chance fly settling on a man's 

 arm, and I am confident that no man except those that 

 have lived in the Tsetse district and who have closely studied 

 the insect could recognise it at a glance. Thirdly, I fail to 

 comprehend how the Tsetse flies could have been imported 

 alive to England in such a state of health as to be ready to 

 inoculate a horse in the first stable in which they were let 

 loose. I will yield one point, and that is that a man who had seen 

 a horse sufl:"ering in Africa from Tsetse contamination might 

 recognise the symptoms and might possibly look around 

 to see what had caused those symptoms. I have made 

 these remarks because a curious case has quite recently come 

 before me as an expert in Diptera. You have all heard 

 of the late Robert Louis Stevenson, the well-known novelist, 

 and I expect that almost all of you know that he spent the 

 later years of his life in Samoa. A short time ago a student 

 under Professor Poulton at Oxford became possessed of a 

 note-book of K. L. Stevenson's which contained numerous 

 notes of suggested plots, interviews, and poetry intended to 

 be developed for future use, but there was no evidence as to 

 the date of these notes, and the student was anxious to ascer- 



PUOC. ENT. SOC. LONU. III., 1900. E 



