-80- 
Coccida© 
Aonidlella aurantii (Mask.), the California red scale 
Promising results, obtained with spray3 of petroleum oil and 
cube and derris resins, led to a study of the relative susceptibility 
of the resistant and nonresistant strains of this scale. YYhen the 
two strains were sprayed with the oil-cube resin the resistant strain 
showed a greater survival in every case. A light -medium oil with 
cube was just as effective as a heavy oil with it; however, mortal- 
ity when light oil alone was used on heavily infested old wood was 
51.6 percent while heavy oil aone caused a mortality of 58.1 percent. 
Mortality was increased to 92.9 and 91.2 percent by the addition of 
cube resins. Both nicotine and cube in oil gave marked increases 
in mortality of scales on all parts of a lemon tree as compared with 
oil alone. In heavy infestations on old wood the addition of cube 
resins increased the mortality from 12.8, 58 > 1, and 58.6 percent to 
43.9, 91.2, and 94.5 percent for the applications of 1, 1.5, and 2 
percent of oil, respectively. Experiments with a tank-mix oil show- 
ed that the addition of derris resins increased the mortality of the 
red scale, but that 1.14 percent of resins in oil was no more ef- 
fective than 0.57 percent. In regard, to one type of emulsive oil, 
scale mortality was proportionate to the amount of cube or derris 
resins in the oil over a wider range of resin concentrationSe~Cressman 
(123-125 ) ; Cressman and Broadbent (126 ) - 
In recent years the addition of derris resin (25 percent of 
rocenone) in suitable mutual solvents showed promise. Oil-toxicant 
sprays, in which 10 percent of derris resin in dibutyl phthalate 
was added to the oil, resulted in a greater mortality of the red scale. 
The effectiveness of derris and cube extracts was best demonstrated 
by the great increase in the toxicity of a kerosene spray made possi- 
ble by the addition of a stock solution with 39 parts of kerosene 
(resulting in 0.031 percent of rotenone in the kerosene). Used at 
a 10-peroent dosage with 4 ounces of calcium caseinate spreader per 
100 gallons, the toxic kerosene often killed practically all red 
scales hit by the spray. Promising results were also had by soak- 
ing finely ground derris or cube root in unheated kerosene for 30 
minutes. In 1942 the kerosene-rot enone 6pray was not yet recommend- 
ed for it had killed a considerable number of trees. In 1943 finely 
ground cube root (5 percent of rotenone), at 1 pound to 100 gallons 
of spray, was used effectively as a supplement to spray oil. A 
properly prepared oil-toxicant solution will result in more improved 
red scale condition, than oil alone, even at long periods after 
treatment. Few, if any, of the scales succumb to the treatment if 
oil alone is used, but if derris or cube extractives are added to 
tne oil, a large percentage of scales not receiving enough oil for 
suffocation are nevertheless killed by the treatment.— Eb el ing (153 - 
156 ); Ebeling and LaDue ( 157 ). 
