The nature of this plague to human kind is shown by a state¬ 
ment in Agassiz’s “Lake Superior" (p. 61) written in July, 1850, 
by J. Elliot Cabot, who prepared the narrative of the Agassiz tour. 
“Neither the love of the picturesque, however, nor the interests 
of science, could tempt us into the woods, so terrible were the 
black-flies. This pest of flies, which all the way hither had con¬ 
fined our ramblings on shore pretty closely to the rocks and the 
beach, and had been growing constantly worse and worse, here 
reached its climax. Although detained nearly two days, 
* * we could only sit with folded hands, or employ ourselves 
in arranging specimens, and such other occupations as could be 
pursued in camp, and under the protection of a ‘smudge.’ One, 
whom scientific ardor tempted a little way up the river in a canoe, 
after water-plants, came back a frightful spectacle, with blood- 
red rings round his eyes, his face bloody, and covered with punc-, 
tures. The next morning his head and neck were swollen as if 
from an attack of erysipelas. Mr. S. said he had never seen the 
flies so thick. * * * * He consoled us, however, by the in¬ 
formation, that it was nothing to what they have farther north.” 
The species of that region are S. vennstum (Figs. 16-22, pp. 
45-46) and S . vittatam (Figs. 23-25, p. 47), both common in cen¬ 
tral and northern Illinois. 
These northern species are also referred to by Dr. A. S. Pack¬ 
ard in his book on “Our Common Insects,” published in 1873. 
“The Labrador fisherman,” he says, “spends his summer on the 
sea shore, scarcely daring to penetrate the interior on account of 
the swarms of these flies. During a summer residence on this 
coast, we sailed up the Esquimaux River for six or eight miles, 
spending a few hours at a house situated on the bank. The day 
was warm and but little wind blowing, and the swarms of black- 
flies were absolutely terrific. In vain we frantically waved our 
net among them, allured by some rare moth; after making a few 
desperate charges in the face of the thronging pests, we had to 
retire to the house, where the windows actually swarmed with 
them; but here they would fly in our faces, crawl under one’s 
clothes, where they even remain and bite in the night. The chil¬ 
dren in the house were sickly and worn by their unceasing tor- 
ments; and the shaggy Newfoundland dogs whose thick coats 
would seem to be proof against their bites ran from their shelter 
beneath the bench and dashed into the river, their only retreat. 
In cloudy weather, unlike the mosquito, the black-fly disappears, 
only flying when the sun shines. The bite of the black-fly is often 
severe, the creature leaving a large clot of blood to mark the 
scene of its surgical triumphs.” 
