ae: 
Control of Horse Flies and Deer 
Flies. --Pyrethrum sprays have been 
used with some success in protecting 
dairy cattle from horse flies and deer 
flies. A thorough coverage with the 
pyrethrum-piperonyl butoxide spray, 
as described for stable fly control, will 
usually protect the animals for about 
2to3days. Methoxychlor shows little 
repelling action, but for 2 to 3 days 
after treatment a high percentage of the 
feeding flies are killed. 
Use of Oil Sprays.--Mostdairymen 
are familiar with the oil sprays for 
controlling flies on cattle. They may 
contain pyrethrins alone or plus other 
materials such as piperonyl butoxide, 
or from 3 to 5percent of certain organ- 
ic thiocyanates. The oil used in such 
sprays is usually a refined kerosene. 
Notmore than 1 ounce of spray should 
be applied with a fine-mist sprayer, 
moistening only the outer coat of hair. 
These sprays are usually applied at 
milking time and may be necessary at 
each milking to provide satisfactory 
protection against flies. It is impor- 
tant to follow directions carefully in 
using such sprays, because, unlike 
water sprays, oil will severely burn 
or even kill cows if the skin becomes 
wet with it. 
Treatment of Dairy Barns 
For controlling house flies and 
stable flies in and around dairy barns, 
the following recommendations are 
made: 
