30 - 
value v;hen used in this v;ay* On the derris-treated plot nimerous earth-- 
v/oms vere found lying dead on the surface and also some slugs. Derris 
powder clearly does not render the bait distasteful to the pests naned, 
as appeared to "oe the case v/ith sodium fluo silicate. The derris bait v/as 
composed of 10 pounds of bran and half a pound of derris powder distributed 
over half an acre of oats, Thompson concluded that derris powder gives 
moderately good results, 
De Long (21) in 1928 reported that a commercial derris product 
diluted 1 to 250 proved unsatisfactory against the potato leafhopper, 
Empoasoa fabae Harris. 
Gamian (38) in 1928 reported experiments made in Connecticut v-ith 
insecticides offered as substitutes for nicotine sulphate. One of the 
commercial preparations of derris was tried in -1927 against the mealy 
plum aphid and showed good killing power, although it failed to accomplish 
a thorough clcan-up on account of poor spread. It is quite evident that 
soap or casein limo is needed in combination. The product investigated 
does not nix well with winter-strength lime-sulphur solution. 
Both derris and pyrcthinam have considerable value as aphicidcs, 
but their success for orchard use will depend on their ability to 
combine with other insecticides and fiingicidcs. The present cost docs 
not seem to be any lower per 100 gallons of spray mixture than nicotine 
sulphate, a.nd no reliable information is available regarding their 
keeping qualities. The only advantage that can be seen from using the 
above-mentioned aphicidcs in an orchard" will lie in increased safet;'" 
of the operator. 
Tests with derris and pyrethrum agr.inst the mealy plum aphid gave 
the follov/ing results: 
Percent 
Substances (commercial preparations) Dilution of kill 
A. Derris preparation 1 oz. to 6 gal 88,3 
B. Derris preparation 2 oz, to 6 gal 97,6 
C. ■ Pyrethrum soap 2 lb. to 3-3/4 gal 94.4 
D. Hicotino sulphate 1 oz. to 6 gal. . .- 92,2 
E. Chech, no treatment 0* 
Gibson (43) in 1928 reported that under laboratory conditions 
powdered derris root dusted on the surface of water in shallow trays at 
the rate of 15 pounds to the acre of water surface destroyed .M^ofj-l ■.•_'vae 
in^a pe:.-iot. ri-mginf^ from 3 to 22 hours, and pupae in from 2 to 5 days. 
In an experiment conducted by lir, Twinn at Hawkesbury, Ontario, it was 
noted that when the powdered derris root was dusted on the surface of 
polluted pools of water heavily infested with Culex pipiens larvae, at 
the rate of 30 pounds to the acre of water surface, 97 percent of the 
larvae were destroyed in 48 hours and 100 percent in 72 hours. 
