-41- 
. T^o percent of Lethane 384 caused a knock-dorm of 100 percent 
in 4. minutes; 3 percent; 100 percent in 3 minutes; end 4 percent, 
100 percent in less than 3 minutes. A combination of 2 percent of 
Lethene 384 end 0.5 pound of pyre thrum yielded r knock-down of 100 
percent in 3 minutes, that is, slightly faster then the 2-percent 
solution of .Lethane- 384 alone, and much faster than 1 pound of 
pyrethrum alone. T'-o-percent Lethane 384 plus 0.05 oercent chemi- 
cally pure rotenone makes a spray causing 100-percent knock-down 
in. .less than 4 minutes, or is practically equal to 2-percent 
Lethane 384, and much faster than any of the rotenone solutions 
used alone. The data on the killing po ir, er of these sprays show 
that, the- substitution of pert of the pyrethrum or of the rotenone 
with relatively smell percentages of the Lethane 384 not only greatly 
increases the knockdown power but also increases the killing -oower. 
The mixture of Lethane 384 and rotenone gave a kill of 33 percent 
in 48 hours. 
The United States Department of Agriculture, Bureau of 
En-tomology and Plant Quarantine (290) .in "1936 reported that sus- 
pensions of the -pondered roots of certain rotenone-bearing plants 
and extracts of these plants ^ere outstanding in their effectiveness 
against the eggs of the Housefly. ■ • 
.H.' E. Whitmire, of the 'Whitmire Research Corporation^ in a 
letter to R. C. Roark, dated February 24, 1936, said that a series 
of rotenone derivatives ranging in melting point from 120° to ™?ell 
over 200° C. had been prepared. The one melting at 178° is called 
Rotoxlene. Rotoxlene in concentrations ranging from 15 to 100 mg. 
per 100 cc. in a mixture of ethylene dichloride 5 percent, pine oil 
5 percent, and .kerosene 9Q percent gave knock-do^ns according to 
the standard Peet-Grady method ranging from 27 to 96 percent in 
10 minutes end final kills' ranging from 27 to 95 percent at the end 
of 48 hours. A screen painted with a solution of 1 pound of -Rotoxlene- 
in 100 gallons of oil (0.12 percent) killed every fly that came in 
contact with it. In a letter dated A-oril 14, 1936-, ^/hitmire reported 
that at a concentration of 50 m?.' per 100 cc.' of a 50:50 by volume 
mixture of ethylene dichloride and pine oil, Rotoxlene gave a 
knock-down of 92 percent in 10 minutes according to the standard 
Peet-Grady fly spray test; also 92 percent dead at the end of 48 
h our s . ' 
r i(orsley (327) in 1936 dusted the "Doddered bark of Liundulea upon 
houseflies. The' flies were dead after 10 to 12 hours, whereas 
pvrethrum killed in 8 hours. Derris containing 5.4 percent of 
rotenone acted' similarly. Kerosene extracts (10 percent) -of Mundulca 
bark, had a strong repellent ecti'on on houseflies. Several hours 
later dead flies could be picked up. 
Baderts.cher ( 12) in 1937 reported th'-t in'order to ascertain 
the true value of a semiconcentrate or a high-kill surey the material 
should be diluted to such "a concentration 'that its killing po'^er 
'"ill fall somewhere near the 50-percent kill mark or - 1 least should 
closely ap-oroximate th^t of the 0. C. I. (Official Control Insecti- 
cide) of the National Association of Insecticide and Disinfectant 
ivianufacturers. The 0. C. I. contains about 90 mg, of r>yrethrins 
