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In Deli, Sumatra, a 1-percent solution, to "which is added 
0.5 percent of soap, is used successfully against aphids. 
The liquid, however, keeps its efficiency for a few days 
only. The Dqtch proprietary insecticide known as Phyto- 
philine probably also contains derris, but it is far too 
expensive. 
According to an anonymous writer (2) in 1930, a spray containing 
as little as 0,025 percent of derris extract (obtained by extracting 
with water) is effective as a contact poison for aphids. 
Corbett (52), entomologist for the Federated Malay States Depart- 
ment of Agriculture, in 1930 reported that plants regularly sprayed with 
tuba at the rate of 1 pound to 10 imperial gallons of water will be kept 
comparatively free from aphids and similar insects. 
Peyer ( 228 ) in 1C30 recommended a spray made by adding 1 kg. of 
derris powder and l/2 kg, of soap in 100 kg. water for control of sucking 
insects. Schmitt ( 240 ) in 1930 in a discussion of derris stated that 
different kinds of leaf lice were controlled by derris dust or by derris- 
extract spray. 
The "Wageningen Plantenziektenkundigen Dienst ( 291 ) in 1931 reported 
that derris was unsatisfactory for the control of leaf lice on various 
plants in the field at Aalsmeer. 
Betrem (14) in 1931 coir> pared imported ground derris with nicotine 
as a control for black aphids in the entomological laboratory in 
Wageningen, Holland. No details were given, but the results were very 
disappointing. The author pointed out that this was probably due to poor 
quality of sample, and discussed the need of judging derris by its rote- 
none content, and not by its total ether extract, because there is no 
correlation between them, according to figures from Spoon. He also dis- 
cussed briefly the methods of using derris, the advisability of adding 
soap, and the manner in which it kills insects, Derris is entirely 
harmless to plants, whereas nicotine sometimes burns. Betrem believes 
that derris is the coming insecticide for greenhouse use. 
Katakilla should be applied as a spray at 0,5 to 0,75 percent con- 
centration a'gainst aphids. — Deutscher Pflanzenschutzdienst (78) in 1931, 
Andries (10) in 1932 recommended Derrisol and Katakilla for use 
against "green fly" (aphids). 
Goff and Tissot (129) in 1932 reported that extracts of derris 
are scarcely more effective than nicotine against aphids, and as there 
is little difference in cost their use has not become general. Like 
the pyre thrum sprays, the derris extracts are somewhat more effective 
than nicotine against some of the larger, more resistant insects. 
Certain activators, such as sodium and ootassium cleates, pine tar soaps, 
and a sulfonated oil product, increase the effectiveness of the derris 
sprays slightly. 
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