-;,.18 - 
The alcoholic ard "benzene e:ctracts of derris, v/hen sufficiently- 
strong and used '.vith soap or kerosene emulsion, were fcond efficient 
against nany species of aphids. The alcoholic extract, used with soap, 
was efficient against half-grown gav/flj- larvae, "but inefficient against 
small v/e'D'.yorms (first instar) and the larvae and adults of potato "beetles, 
At Tallulah, La., a commercial preparation of powdered derris v'as 
used on three dogs which were infested with fleas, Ctenocephalides canis 
Curt, It wa.s found efficient against the floas. 
Fu.lnek (34) in 1924, in discussing insecticides for use against 
tohacco pests in Sunatra, listed alcar tu'oa as a contact insecticide. 
The addition of 0.3 to 0.5 pcrCGnt of soap to solutions of derris is 
advised, 
?ulinok (35) in 1924 recommended akar tu"bj, for loaf lice at the 
rate of 1 kilogram in 100 liters of water to which 0,5 kilogr>am of sc/p 
is added. 
1925 
Gator and Yusopo (40) in 1925 stated that the usual aqueous derris 
extract as made in Britisli L'alciya would form an effective spray against 
young caterpillars of L ae 1 i a suf f o sa V/lk. damaging padi, 
G-ater (39) in 1925 reioorted dipping tests with mature larvae of 
Parasa her"bifera V/alk. , larvae of Tirathalpa sp, , and nymphs of D^'sdercus 
cingalatus F, The latter is particularly suscepti"ble to derris. Gater 
concluded tha,t the insecticidal constituents of derris are almost if not 
completely destroyed "by the digestive fluids of a "bostrichid, 
Ualton (106) in 1925 reported -that preliminary trials of derris 
ointr.iont prepared according to the formula of UTells, Bishopp, and 
Laakc (109) had "been made for the control of war"ble flies in I^orth Ualos. 
The results o"btained with 91 cattle were most promising, 
Bourcart (9) in his "book Insecticides, Fungicides, and Weed 
Killers, English translation of 1925, stated that a spray containing 
1 pound of derris, 10 imperial gallons of water, and 5 ounces of soft 
soap is effective against aphids infesting to"bacco in Sumatra, The 
derris roots, which may "be dr^^^ or fresh, are cut into small pieces, 
placed in a little water, and then pounded into a paste, which is 
diluted v;ith a gallon of water and left standing overnight in a wooden 
vat. An iron container must not "be used. The dregs are then pressed, 
and all the fluid is straineql through a cotton cloth,. The resultant 
concentrate is a milk-v/hito solution, which keeps for a few da.ys only. 
It is diluted with 9 parts of water for spraying, A"bout 16 imperial 
gallons of solution arc needed for 1,000 tobacco plants that have "been 
25 to 30 days in the field. Twice this quantity is needed for full-grovm 
plants. If derris roots arc to "be stored, they must be kept dry. 
