SS2 Mr Cornelius on a singularly Poisonous 
first remarked during a snow storm in the winter of 1807 , when 
its effects upon cattle and horses were observed to be similar to 
those of the gnat and musquito in summer, with this difference, 
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 travellers. So far as I recollect, it was stated that 
from thirty to forty travelling horses were destroyed during 
this winter. The consequences were alarming. In the wilder- 
ness, where a man’s horse is his chief dependence, the traveller 
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 it unfit for use. 
Unwilling to believe that effects so dreadful could be produced 
by a cause apparently so trifling, travellers 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 a distance 
of forty or fifty miles, their own provisions ; but, after all, suf- 
fered the same calamities. This excited a serious inquiry into 
the true cause of their distress. The fly which has been men- 
tioned, was known to have been a most singular insect, and pe- 
culiarly 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 now it happens that comparatively few horses are 
destroyed. I am 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 colour is a dark brown ; it has an elongated 
head, with a small and sharp proboscis, and is in size between 
the gnat and musquito. When it alights upon a horse, it darts 
through the hair much like a gnat, and never quits its hold un- 
til removed by force. When a horse stops to drink, swarms 
fly about the head, and crowd into the mouth, nostrils, and 
