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lervae in the backs of cattle. 
^ecDougall ( 185 , 186 ) 'in 1924 reported tests wit& a proprietary 
preparation of derris. Any scab and rnetted hair obscuring the exit 
hole of the larva in the skin ^s cleared away before the dressing 
was applied. One ounce of derris to 1 imperial ouart of "-ater killed 
86 percent, and 1 ounce' to 1 pint killed 94 percent of the parties. 
No injurious effects attended any of the cattle dressed with derris 
and there '-es no discomfort to the hands of the dresser. MacDougall 
( 187 ) in 1928 reported that two dressings of service against Hypo- 
derma larvae, tested in Sootland in 1927, averaged good results. -.. 
first was one in great favor in Denmark, viz., Kypoderma oil.' This 
costs 5 pounds per gallon, but a little goes a .long way. It was 
injected by means of a syringe at the opening into the warble, the saueez 
hole being first cleared. Three or 4 days later the treated ^prbles" 
"ere examined and the larvae ^ere/out. While Hypoderma oil <iid not ' 
do all the advertisements claimed for it, it can te recommended. It 
was most successful against the youngerlervee. Last— stage larvae 
^ere much more difficult to kill. Treated cattle did not suffer in 
health, and there was no falling out of hair. ittecDougall, ( 188 ) 
in 1930 reported that Kur-Mange at 1 ounce per imperial auart of 
rater killed 86 percent of Hyoodj3rma_ larvae in the backs of cattle, 
end at trice this concentration killed 95 percent. 
MacDougall ( 189 ) in 1931 reported on the campaign against ox- 
warble flies in Scotland in 1930. The following derris preparations 
"ere effective against the larvae: Polvo powder 1 pound, soft soap 
1/4 pound, water 1 imperial gallon; Garble Fly Ponder 1 pound and (190) 
water 1 imperial gallon. In 1932 he/Teported- that in Scotland in 
1931 three different kinds of dressing were tested, vi-!;.: polvo soft 
soap as in 1930; Warble Fly Powder (with the soap already incorporated 
and needing only the addition of water); and e liouid derris preparation. 
The first two '"ere v^ry successful. l-lacDougall ( 191 ) in 1934 reported 
tests on control -ork in Scotland with the following proprietary derris 
products: Bovidere oil, Cooper's Warble Fly Ointment, Cooper's Warble 
Fly Powder, Cooper's Cattle Wash, and P-lvo. Ninety- three percent 
of the marbles were killed. 8 days after the application o-f polvo powder 
soap '"ash containing derris ponder 1 pound, soft soap 1/4 round, and 
water 1 imperial gallon, at the rate of 3/4 gallon per animal. The 
cost of material was about 2 cents per animal per application, and the 
total cost was about 25 cents per animal for 4 applications. Tests 
w< re also made "-ith cube powder, ^sing the proportions 1/4 pound of 
the powder to 1 imperial gallon of water, 43 *»erbles were dressed and 
on examination, 25 larvae were dead, 5 "ere alive, end 13 burst in 
being squeezed out. Using 1/2 pound of the powder to 1 imperial gal- 
lon of rater, 42 larvae were treated and on reexamination 30 larvae 
were dead, 1 ™?s alive, and 11 burst in bein:- squeezed, out* 
Walton (304) in 1925 reported that preliminary trials of derris 
ointment prepared ecc rding to the formula f ""--lis, Bishopp, end Laeke 
had been made for the cohtr 1 f warble flies in North Wales. 1 hc 
results obtained with 91 eattli were most promising. 
e^ 
