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Pedretti ( 229 ) in 1936 reported on the control of Hypo derm a 
larvae -ith derris^ preparations. T»6t6 wsre -made with Abdsssol, 
Derrilavol,- Eer'risol, Derrop.hen, and Laurus-Desselpulver. 
Bartels (17) in 1937 reported that derris prepare tions gave a 
high percentage of control of Hypoderma larvae. 
Hard tmann( 137) in 1937 stated that for combating wc-rble fly 
larvae in the skins of cattle, oil snrays containing 0.05 percent 
of rotenone were employed. 
The Louisiana Agricultural Experiment Station (184) in 1937 
reported that derris ^o^der dusted into the warble holes killed a 
high percentage of grubs, 
Natvig ( 210 ) in 1937 reviewed ^ork on ox warble flies in :or~ay 
and stated that various '-ashes, including derris, wre used. 
The Ruhderhorzel-Bestrijdings-Commissie ( 245 ) of Holland, in 1937 
recommended aqueous susnensions of derris root for control of cattle 
grubs. 
An anonymous (7) writer in 1 938 reported on the ^arble flv pest 
in England. The percentage of hides with open marbles handled by 
the Hide Improvement Society during the first 9 months of 1938 '-as 
s lightly greater than in 1937, but less then in 1936. Derris sales 
in 1937 and 1938 were much less than in 1936. The Ministry of Agri- 
culture held that rigid enforcement of the Warble Ply (Dressing of 
Cattle) Order would only antagonize farmers gener=lly end defeat its 
own object. "Enforcement should be tightened up gradually, cut at 
the present the Order should be the background for an educational 
and propaganda campaign, bringing home to farmers their obligations 
under the Order and the advantage to themselves of rving its 
provisions. The number of prosecutions report 3 the Ministry 
during 1938 was 94, against 51 in 1937, and 8 i.. J ?5. 
The United States Department, of Commerce, Bureau of Foreign and 
Domestic Commerce ( 301 ) in 19"40 called attention to an order of the 
British Ministry of Agriculture making the use 3f preparations 
for cattle dressing obligatory. This is a mcdificeti n f the 
"Warble Fly (Dressing of Cattle) Order of 1936." The original order 
permitted the removal of maggots from the skins of affected cattle 
by mechanical means. This alternative was later withdraw and it 
wad reauired that all visibly infested animals be treated during 
the current season by the application at monthly intervals of a 
derris dressing prer^red according to specifications in the order. 
Edwards (79) in 1938, in a. popular account of rotenone-containing 
insecticides, stated that they were effective against warbles on c?ttl<j 
