DIPTERA. ~ 41 
and it probably occurs in localities throughout much of the British 
provinces, its local distribution depending upon the occurrence of 
swiftly running streams, which are essential to the life of the larve. 
The larval form has not been positively identified, but Dr. Packard 
figures a specimen which he collected in Labrador and which he sup- 
poses to be the larva of molestum or a closely related species. 
THE SOUTHERN BUFFALO GNAT. 
(Simulium pecuarum Riley.) 
EARLY HISTORY. 
In the American Journal of Science (Vol. I, 1818) there occurs on 
page 328, under the heading, “A destructive insect,” the following 
interesting account, which must certainly refer to the buffalo-gnat, and 
which is, so far as I know, the earliest authentic account of its operations: 
But I will not enlarge upon a fact already familiar. Iwill ask your further indul- 
gence only while I communicate an authentic and curious fact for the information 
of the zoologist. 
In the Choctaw country, 130 miles northeast of Natchez, a part of the public road 
is rendered famous on account of the periodical return of a poisonous and destruc- 
tive fly. Contrary to the custom of other insects, it always appears when the cold 
weather commences in December, and as invariably disappears on the approach of 
warm weather, which is about the Ist of April. It is said to have been remarked 
first in the winter of 1807, during a snowstorm, when its effects upon the horses and 
cattle were observed to be similar to those of the gnat and mosquito in summer, 
except that they were more severe. It continued to return at the same season of the 
year, without producing extensive mischief, until the winter of 1816, when it began 
to be generally fatal to the horses of travelers. So far as I recollect, it was stated 
that from thirty to forty traveling horses were destroyed during this winter. The 
consequences were alarming. In the wilderness where the man’s horse is his chief 
dependence, the traveler was surprised and distressed to see the beast sicken and die 
in convulsions, sometimes within three hours after encountering this little insect. 
Or, if the animal were fortunate enough to live, a sickness followed, commonly 
attended with the sudden and entire shedding of the hair, which rendered the brute 
unfit for use. Unwilling to believe that eftects so dreadful could be produced by a 
cause apparently so trifling, travelers began to suspect that the Indians or others, 
of whom they obtained food for their horses, had, for some base and selfish end, 
mingled poison with it. The greatest precaution was observed. They refused to 
stop at any house on the way and carried, for the distance of 40 or 50 miles their 
own provisions, but after all suffered the same calamities. This excited serious 
inquiry into the true cause of their distress. The fly which has been mentioned was 
known to be a most singular insect, and peculiarly troublesome to horses. At length 
it was admitted by all that the cause of the evils complained of could be no other 
than this insect. Other precautions have since been observed, particularly that of 
riding over the road infested with it in the night; and it now happens that compar- 
atively few horses are destroyed. Iam unable to describe it from my own observa- 
tion. I passed over the same road in April last, only two weeks after it disappeared, 
and was obliged to take the description from others. Its color is a dark brown. It 
has an elongated head, with a small and sharp proboscis, and in size between the 
gnat and mosquito. When it alights upon a horse it darts through the air, much 
like a gnat, and never quits its hold until removed by foree. When a horse stops to 
drink swarms fly about the head and crowd into the mouth, nostrils, and ears; 
