-80- 
Coccidae 
Aonidiella aurantii (Mask,), the California red scale 
Promising results, obtained with sprey3 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* When 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 concentrations*~Cre8sman 
(123-125 ) j 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 spray 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)* 
