49 
general, have any relation to the occurrence and frequency of 
cases of pellagra, would require a very much broader and closer 
survey of the state with this point especially in mind than it has 
been possible for me to make. With the exception of a part of 
the data obtained at Havana and Peoria in 1910, those here re¬ 
ported are the product of general miscellaneous collections made 
during many years, with no thought of any pathological applica¬ 
tion. They are sufficient, however, to show the common occur¬ 
rence of black-flies thruout the state. Our specimens have come 
from sixteen counties—five in northern Illinois, eight in central, 
and three in southern, as follows: northern Illinois—McHenry, 
Carroll, Cook, La Salle, and Mercer; central Illinois—Peoria, 
Tazewell, McLean, Vermilion, Champaign, Mason, Fulton, and 
Greene; and southern Illinois—Wabash, Saline, and Jackson. 
The places and situations of occurrence are such as to war¬ 
rant the opinion that black-flies might be found in larger or smaller 
number in every county of the state. They would be most abun¬ 
dant, of course, along the larger rivers (and it is only there that 
they become noticeable as pests), and the species would differ 
with the size and character of the streams, and to some extent 
with the latitude. 
The only attempt I have been able to make towards a com¬ 
parison of local facts concerning Simulium with the local data of 
pellagra, is based on observations made at Bartonville, near Peo¬ 
ria, in the latter part of August, 1910. The location there of the 
General Hospital for the Insane, in which pellagra is almost con¬ 
tinuously present, gave us reason to examine the surroundings of 
this institution as carefully as possible; and visits were made to 
this place by Mr. C. A. Hart on the 29th, 30th, and 31st of Aug¬ 
ust. In a small stream just north of the hospital grounds at 
Bartonville, which leaves the bluff on which the buildings stand, 
passes under the highway, and flows eastward thru low ground 
towards the river, Simulium larvae were obtained just below the 
wagon bridge, on the leaves of trailing branches and on other 
objects in the stream, altho none could be found in this stream 
above the highway. The point at which the black-flies were 
breeding was about a third of a mile in a direct line from the 
hospital buildings. No pupae were seen in the water, and no 
winged flies could be caught by diligent sweeping of the vegeta¬ 
tion in that vicinity. Two small streams emerging from shady 
valleys in the bluffs to the south of the hospital grounds were 
destitute of Simulium larvae. 
In Kickapoo Creek, between Bartonville and Peoria, a very 
few larvae and pupae were found, and a considerable number were 
taken in favorable places all along Farm Creek near the East 
