-8- 
The cold alcoholic' extract of cube used without soap was effect- 
ive. A water extract of a species of Lonchocarpus had no effect. 
A commercial derris powder was effective. Used as a fumigant ^burned 
it was also effective. — ? : cIndoo and Sievers ( 263 ) in 1924. 
Gross and Fahey ( 170 ) in 1930 referred to tests made by F. L. 
Campbell, which indicated that rotenone as a stomach poison is 
30 times as toxic to silkworms as is lead arsenate. 
F. L. Campbell ( '60 . 61 ) in 1932 reported results by Davidson. 
Rotenone suspended in water 1:1,00.0 sprayed on leaves and fed to 
the third instsrs as a sandwich killed all; at 1:5,000, 40 percent 
were killed, f.'ore precise results were obtained by Campbell with 
fourth ins tars. Using the sandwich method as described by Campoell 
and Filmer, Campbell- found the median lethal dose of rotenone to 
be about 0.003m§» P er g 01 * Since the m.l.d. of acid lead arsenate 
for the fourth instar is about 0.09 m g« per gn^ rotenone is about 
30 times as toxic as acid lead arsenate for this inssct. In two 
of his tests Davidson did not kill all the silkworms. In his 
quantitative tests of various stomach poisons Campbell found that 
the most obvious effect of nearly lethal doses is to prevent the 
larvae from feeding oh untreated leaves for a period that depends 
on the quantity of the sublethal dose. When lethal doses of roten- 
one are taken, the silkworm does not eat again, but may remain 
alive for several days. The toxic action of rotenone is slow as 
compared with that of established insecticides, and the silkworm 
is so slowly affected by ro'tenone that it may take a dose many 
times as large as the median lethal dose. The quantity of roten- 
one that an insect may eat in excess of the median lethal dose 
depends on the concentration of rot?none on the foliage, the feed- 
in? habits of the insect, and its specific reaction to rotenone. 
Dr. Campbell also reported in 1932 that the m.l.d. of malachite 
green for fourth instars is about 0.025 m g. per gnu 
Ginsburg( l63 ) in 1932 reported experiments with waxes as 
possible carriers of insecticides. An emulsion containing 1 percent 
of spermaceti, derris-root extract 1:400, and 0.2 percent .of tri- 
ethanolamine oleate caused a mortality of 96 percent after 72 
hours. Similar tests with paraffin (42° m.p.) and with paraffin 
(55° m.p.) instead of the spermaceti gave mortalities of 95 and 
100 percent, respectively. Derris and triethanolamine oleate at 
the same strength without wax gave a mortality of 90 percent. These 
tests were made as follows: Mulberry twigs were sprayed with the 
desired, solutions and placed in vials of water under cages. As 
soon as the leaves were dry, 20 third or fourth inst?rs were 
transferred to the foliage in the cages, 3 or more cages being used 
for each test. After 72 hours, the number of dead and' living cat- 
erpillars was counted. The derris was used in the form of an extract 
equivalent to 1 pound of derris root (4 percent rotenone) to a gallon 
of stock emulsion. Similar tests with a pyrethrum extract equivalent 
tc 1 pound of flowers (0.9 percent pyrethrins) to a- gallon of 
stock emulsion killed less than half as many caterpillars. 
