- 77 - 
Leca nium s, y . 
Derris or rotenone suspensions were ineffective.— DeBussy et al. 
(52) in 1935; also (31) in 1936. 
Not affected by derris. --Van der Laan (178) in 1936 j also DeBussy 
et al. (5JL). 
L epidos a phes beckii (Newm. ), the purple scale 
English (94) in August 1C39 reported on derris as a toxic supplement 
to oil emulsions for the control of the purple scale on sat s una oranges. 
Experiments r/ere conducted on potted plants and in the field. Emulsions 
prepare-;, from several oils and emulsifying agents were used as carriers, 
No control attributable to derris was obtained with an 83-viscosity tank- 
mix oil spray as the carrier; however, derris was effective when used with 
a 41-viscosity tank-mix oil spray and with diglycol laurate. In experi- 
ments with potted plants derris was an effective supplement to mineral- 
seal oil emulsions prepared with diglycol laurate, diglycol oleate, sodium 
oleyl sulfate, or powdered skim milk, or with dried-blood albumen in a tank- 
mix spray. Although the tank-mix emulsion v.ith derris was the most effec- 
tive spray applied to potted plants, the increase in effectiveness attrib- 
utable to derris mas low, and positive field results were not obtained. 
Greater increases in kill attributable to derris were obtained rath emul- 
sions prepared from diglycol laurate, diglycol oleate, and sodium oleyl 
sulfate. Both derris and Derris ql, when used 'as' supplements to a 2-percent 
emulsion prepared from mineral-seal oil and diglycol oleate, reduced 
significantly the percentage of scaly fruit on field plots. An experiment 
with extracted and unextracted derris showed that derris vas a true toxi- 
cant to the purple scale, 
Lepi dosaphes ulmi (L.), the oystershell scale 
Kclndoo, Sieve rs, and Abbott (189) in 1919 reported that derris 
applied as a dust was of no value against the crawling young of the 
oystershell scale, 
Orthezia ins i gnis Dougl., the greenhouse orthezia, or lantana bug 
Mclndoo, Sievers, and Abbott (189) in 1919 reported that derris 
applied ae a dust was of no value against the orthezia. 
Worsley (324-) in 1956 reported as follows concerning bark of 
Mundulea suberosa Benth. (0.9 percent rotenone) from Moa district, Tan- 
ganyika Territory, East Africa, and derris root (5.4- percent rotenone): 
Both derris and Mund ulea bark killed 100 percent of 0. ins ignis at a 
concentration of 2 percent, but a concentration of 7.5 percent nicotine 
was required for 100-percent kill, 
Phenacoccus aoeris (Sign.), a mealybug 
Derris sprays were ineffective,— Patterson (221) in 1936, 
