INSECTS INJURIOUS IN 1902. 35 
Treatment in the case of very large herds is naturally beset 
with difficulties. Moist weather, by keeping the dung moist for a 
longer period is most favorable for the development of the Horn 
Fly, while any method of destroying the dung will lessen the 
chances for its successful increase. A decoction of a species of 
Smart Weed (Polygonum pennsylvanicum) was tried, one pound 
in three quarts of water boiled down to two quarts, with absolutely 
no results. It is to be hoped that none of our farmers will be 

Fig. 33.—A species of Smart Weed (Polygonum pennsylvanicum). 
led to follow the example of a gentleman living at Hills, Minne- 
sota, who unwittingly applied machine oil to a valuable horse with 
very serious consequences, the hair coming off completely and 
leaving the skin in a raw, sore condition. We realized no bad ef- 
fects in this way after treatment with the above compounds. 
This year the Horn Fly began to be troublesome early in Au- 
gust. A few individuals can still be observed about the cattle 
at this date, Oct. 6th. It is perhaps of interest to note the fact 
that while Flesh flies and Green Bottles frequented the surface 
