-55- 
Bishopp, Laake, Wells end Peters (32) in 1930 reported that ex- 
cellent results "'ere obtained in tests made against Hypo d erma larvae 
in the backs of cattle by the use of powdered cube root, powdered 
derris root, derris extract in kaolin, derris resins in petrolatum, 
and a proprietary derris-extract ointment. No toxic effects on the 
cattle are to be expected from derris products and they do not seem 
to injure the skin. Derris powder fron which the rotenone had been 
partially extracted with ether killed 33 percent of the grubs, in- 
dicating that the other constituents have insecticidal value. Kaolin 
containing not less than 2 percent of rotenone gave almost a complete 
kill. 
Bishopp (28) in 1941 reported that, for killing cattle grubs, 
derris powder should obtain at least 1 percent of rotenone and 
should be ground fine enough to allow 90 percent of it to pass through 
a 200-mesh sieve. Although apparently not so effective as ground derris 
root, certain -powders to which from 1 to 2 percent of rotenone or a 
proportionate amount of derris extract had been properly added were 
satisfactory. A wash consisting of derris ponder 1 pound, water 1 
gallon, and soap 2 ounces, brisklv rubbed in with a brush, gave a 
100-percent kill in many cases. 
'1' 
he United States Department of Agriculture, Bureau of Entomology 
(282) in 1923 reported the "'ork of Bishopp et al. Over 98 percent of 
the grubs can be killed with a general amplication of pondered derris ' 
root to the backs of cattle . A wash consisting of 1 pound of derris, 
4 ounces of soap, and 1 gallon of water also gave a kill above 95 
percent. An ointment consisting of 1 part of derris and 5 parts of 
vaseline gave almost 100-percent kill when the material was -pressed (283') 
into each hole. The same Bureau/ in 1927 reported that tests with 
insecticides against cattle grubs in Virginia indicated that pondered 
derris root '"ill give a high percentage of kill if applied and brushed 
in at intervals of about 20 days. The Bureau ( 284 ) in 1929 referred 
to experimental ir -ork done with insecticides applied to the becks of 
cattle, special attention being given to rotenone and other materials 
extracted from derris root. The report stated that these insecti- 
cides show high toxicity to cattle grubs and can undoubted.ly be 
developed to a point where they c?n be extensively used in control 
""ork. In 1930 the Bureau reported that 2 or more ounces of derris 
powder per animal are necessary if the entire back of each animal is 
to be treated. The Bureau ( 286 ) in 1931 stated, that derris end its 
derivatives appeared to be- the most promising insecticides for the 
control of cattle grabs, particularly as there is no danger of (288) 
poiBoning livestock with them. In 1933 the Bureau/ reported that 
various insecticides for killing the grubs in the backs of cattle 
by hand application had. been tested. Rotenone, in combination with 
benzol, w 5s found to be highly efficient. One-half gm. of rotenone 
was dissolved in 100 cc. of benzol, and approximately 1 cc. of the 
fixture was injected into the opening of each cyst. This method of 
treatment is relatively fast, as compared ^ith any other treatment 
epnlied to grubs individually. 
Wer&le end Buckle (307) in 1933 referred to the derris ^ash 
recommended by Wells, B ishonp, and Laake in 1922 for killing Hynoderma 
