38 
The fact that it commonly appears on the wing but once during 
the year, its usual period in the South being about six weeks in 
spring, points to the conclusion reached by Riley that it has but 
one annual generation. In Louisiana this is abroad in February 
and March, but in New Mexico it is said by Townsend to have 
been abundant in 1891 from the middle to the last of May, appar¬ 
ently continuing thru the month of June. In the year 1891 it was 
common on the lower Red River in Louisiana in December, Janu¬ 
ary, February, and March—a fact attributed by local observers to 
the unusually warm and open character of the winter. In north¬ 
ern Ohio (Wayne county) adults were abundant May 11, and 
larvae, some of which were very small, and pupae, as well as adults, 
were found on the 16th of May.* In New Mexico, C. H. Tyler 
Townsend found this species (re-described by him as S. occiden- 
tale) swarming May 7, and generally abundant by the middle to 
the last of May. 
Its life history has really not been traced, and nothing is known 
of the stages or places in which it passes the summer and fall. It 
hibernates as a larva, and pupates in spring. It is one of the three 
or four most notorious and destructive of our American black- 
flies, and joins with the buffalo-gnat (S. pecuarum) in doing enor¬ 
mous damage to live stock and poultry in the southern states. 
A correspondent, James T, Gilliam, of the U. S. Entomologist, 
writing from Charlotte county, Virginia, in 1888, makes a state¬ 
ment especially interesting because of its possible bearing upon the 
function of this gnat as a carrier of the germs of contagious dis¬ 
ease. He reports that in his region it is known as the “cholera- 
gnat,” because supposed to produce chicken cholera. Thousands of 
chickens and turkeys are killed by it every year in that section. 
“I moved to this place in January last,” he says, “and was told that 
it would be impossible to raise chickens or turkeys as the cholera 
would kill them all; notwithstanding which I bought both chickens 
and turkeys, determined to fight the cholera should it appear. Saw 
nothing of it until about the 1st of April, when my attention was 
attracted first by the turkeys shaking and rubbing their heads, and 
upon examination found the gnats upon the wattles sucking vigor¬ 
ously. The gobblers and roosters are the first to succumb, as their 
wattles and combs are larger, exposing a larger surface for the 
gnats to work upon. The fowl grows weak and feverish; the dis¬ 
charge from the bowels becomes frequent and watery, resembling 
*Bull. No. 31, N. Ser., Div. Ent., U. S. Dept. Agr., p. 86. 
