48 
of Cook’s Island), from the Fox River at Ottawa, from various 
streams in Champaign and Vermilion counties, and from creeks 
along the lower Illinois in Greene county. At Muncie, in Ver¬ 
milion county, where larvae alone were common April 20, nearly 
all had pupated by May 3. 
Fig. 23. Fig. 24. 
Fig. 25 
Figs. 23-25. Simulium vittatum’. Fig. 23, front of head of female (x 35). Not re¬ 
liable as to structure of palpi); Fig. 24, thorax and head of female (X 22); Fig. 
25, larva, dorsal view (x 10). 
Its recorded general distribution ranges from Greenland, New 
York, Minnesota, and South Dakota, to Nebraska, Kansas, and 
California. It has not been taken, as will be noticed, from the 
South. It is said by Washburn, in Minnesota, to pay especial at¬ 
tention to mankind, vennstum, commonly associated with it, be¬ 
ing peculiarly annoying there to domestic animals. Hunter's ex¬ 
periments for the transfer of pellagra from human beings to 
monkeys by means of this species of Simulium are reported in full 
in the Journal of the American Medical Association for February 
24, 1912, and an abstract of this article appears in the Journal of 
Economic Entomology for the same month. 
Possible Relations to Pellagra 
To ascertain definitely whether the distribution of black-flies 
in Illinois, and the times of their principal appearance, local and 
