47 
In northern Minnesota, according to Lugger, the earliest gen¬ 
eration is on the wing from May 15 to June 1, and a second in 
June and July; and Sanderson says that in New Hampshire the 
flies are most numerous during early summer and again late in 
the same season. 
The general distribution is similar to that of meridionale and 
peciiarum, the outlying boundaries of its area traversing New 
Hampshire, Canada, Minnesota, Wyoming, Idaho, and British 
Columbia on the north, and Texas, Louisiana, Mississippi, and 
Florida on the south. 
In this state we have taken it from a small swift stream near 
Fountain Bluff in southern Illinois, from Algonquin in the north¬ 
ern part of the state, from the Salt Fork in Champaign county, 
from Spoon River in Fulton county, and from White Oak Run 
near Havana. The latter, a clear, rapid tributary of Matanzas 
Lake, contained larvae and pupae in abundance from May to Octo¬ 
ber. Adults were collected by Dr. Nason at Algonquin on twenty- 
two dates including every month from April to October, from 
trees and other vegetation along a creek, from pastures, vacant 
lots, and gardens, and from the windows of his house. Garman 
found the winged fly emerging from the pupa in Kentucky in 
August or September. This is clearly one of the several-brooded 
species, and probably matures three generations in Illinois. 
S. vittatum Zetterstedt (Figs. 23-25).—Commonly associated 
in the north with the preceding, this species shares with that the 
general name of “the black-fly.” It is our most abundant creek 
species in central Illinois, and the one most likely, in my judg¬ 
ment, to be connected with pellagra in this part of the country. 
It is a several-brooded species, adults having been obtained by 
us April 9 and July 20, and larvae and pupae on sixteen different 
dates from April 4 to September 2, and larvae also on March 12. 
In Kansas adults were used by Prof. Hunter in an inoculation 
experiment with guinea-pigs and monkeys, from the 21st of August 
to the 4th of November. 
If is generally distributed wherever streams of the right char¬ 
acter are to be found, the ordinary gravelly creek seeming to be 
its favorite breeding place. It was not obtained by Dr. Nason 
in his numerous collections, running thru several years, at Algon¬ 
quin, in McHenry county, but has been found by us in Cook and 
Carroll counties in extreme northern Illinois, and also in tribu¬ 
taries of the Saline River in Saline county, in the extreme south¬ 
ern part of the state. In central Illinois we have it from small 
streams near Bartonville and Farm Creek near Peoria, from 
Spoon River in Fulton county, from Quiver Creek and White Oak 
Run, in Mason county, from the Illinois River at Havana ( shore 
