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the injection of substances into the cysts containing the larvae 
show that each of these methods of treatment is 'effective if 
certain materials are used. Berris used as a wash, as an ointment, 
or as a powder is among the most effective of these. 
Walton (305) in 1927 reported on the control of warble flies in 
North Wales. The killing properties of derris appeared to be 
excellent. The ointment (l part of derris powder plus 2 parts of 
soft paraffin) is odorless, and the cost is low. On the other 
hand, the ointment was found to be much more difficult to apply 
and olive oil was utilized, the ointment then consisting of 1 part 
of powdered derris, 1 part of soft paraffin, and 1 part of olive 
oil. This improved the texture and rendered application easier. 
Hypoderma lineatum is the predominant species in North Wales. 
Case (58) in 1929 reported thct six 3- year-old steers in Burkes 
Garden, Va . , infested with ox warbles ( Hypoderma lineatum and H. 
bovig) were treated in March 1927 with derris powder. One animal 
was treated by removing each scab, then sprinkling on the powder 
and rubbing it with the finger tips. At the time of the examination, 
3 days later, this treatment had killed all 5 larvae in the animal. 
The other 5 animals '"ere curried over the back, ribs, and loin with 
a round, spring, stock comb; the powder was sprinkled on by means 
of a shaker can and rubbed- in auickly but thoroughly. This method 
of application caused a mortality of 24 out of a total of 50 larvae, 
MacDougall ( 188 ) in 1930 reported details of experiments carried 
out in Scotland with 5 proprietary dressings for the control of 
H ypoderme bovis and H. lineatum in cattle, A wash of derris powder 
and soft soap gave very satisfactory results, killing 2,785 of the 
3,035 larvae treated. In mixing the wash, care should be taken that 
the boiling water in which the soap. is dissolved is cooled to blood 
heat at least before being poured on the derris powder, or the active 
principle of the latter may be affected. 
Little ( 181 ) in 1931 reported on the insecticidel properties of 
the devil' s-shoestrings ( Tephrosia virginiana ) . The roots dug from 
several localities at various times of the year were dried by different 
methods and then finely ground in an herb mill. Encouraging results 
were obtained on common cattle grubs. 
Later Little ( 182 ) reported in 1931 that the powdered root of 
Tephrosia virginiana dusted on cattle grubs in the backs of cattle 
killed about 90 percent within 10 dfys. 
Bhatia (26) in 1934 reported that the goat warble fly ( Hypoderma 
crossi PettonT~and the cattle warble fly (H. lineatum (De Vill.)) do 
'great damage to goat skins in Indie. Referenoe is made to the 
successful use of derris and Folvo against marble grubs in England. 
