A Bulletin No. 159 



medical men who met at Corbin some time ago with a view 

 to considering the matter and if possible devising means of 

 checking the further spread of the ailment. 



At this meeting it was requested that the writer of this 

 bulletin visit the region in which pellagra is prevalent and 

 determine if any fly occurs there that might serve to convey 

 the disease. 



In response to this request I spent several days at Ccrbin 

 in the latter part of August and in early September, and 

 again in October at Pineville, studying the localities in which 

 pellagrous cases are located, and giving special attention to 

 the streams in the region as breeding places of the flies. 



It may be explained at this point that I was aware that 

 Fall is not the most favorable season to look for the flies. 

 The late Dr. Riley, who studied the buffalo and turkey 

 gnats (Simulium pecuarum and S. meridionale) some years 

 ago, declared indeed that the species were one-brooded. It 

 was known to me, however, that some of our species pro- 

 duce more than one annual brood, and in any case i^; seemed 

 best to study the locality and familiarize myself with the dis- 

 ease in order that I might not lose time in the Spring when 

 the flies of the genus generally appear in great numbers. 



Two species of the flies were known to me to occur in 

 Kentucky at this time. The buffalo gnat (S. vecuarum) 

 was years ago very abundant periodically in April and May 

 along the Ohio and Mississippi Rivers in Western Kentucky. 

 This gnat still occurs locally some seasons in that part of 

 Kentucky, attacking stock and sometimes, it is claimed, in- 

 vading the nostrils of men, causing sneezing, but no other 

 annoyance. The larvae of a second species (5. pictipes) 

 were collected by me in 1893 in large numbers in small rills 

 running into Kentucky River about 14 miles from Lexington. 

 This gnat is said not to sting and hence may be eliminated 

 from the problem. I have also a few specimens of Simulium 

 larvae, not yet studied, collected at Lexington in a small 

 stream, August 5. 1889. 



At Corbin I inspected the surroundings of cases in 

 charge of Drs. M. VV. Steele and J. H. Parker. The weath- 



