-14- 
against the citrns red mite in California. Various concentrations and 
combinations of rotenonq, finely powdered derris, finely powdered cube root, 
pyrethrum extract, finely poudered pyrethrum flowers, free. nicotine, and 
nicotine sulfate were tested under field conditions. None of these products 
as used, even at concentrations that are commercially prohibitive, showed 
sufficient toxicity to the citrus red mite or its eggs to be considered promi- 
sing in control. 
? r- r -' t e t r o n y chu s ilicis McG. , the southern red mite 
7 Michigan Agricultural Experiment Station (103) in 1931 reported that 
Derrisol at 1:300 plus 2 pounds of Ivory soap per 100 gallons killed the active 
raspberry mites that r-ere fairly hit by the spray. In 1932 this station ( 104 ) 
reported that for the control of raspberry mites many sprays were tried, among 
them glue, oils, nicotine, r)yre thrum, derris soap, end as many combinations as 
time permitted. It was finally demonstrated that summer oils used at the rate 
of 1 percent, either alone or in combination with bordeaux, controlled this pest, 
Paratetrenychus pilosus C. & F. , (syn. Oligonychus ulmi Koch), the European 
red mite 
See Moore et al. ( 107 ) under T e trenychus pacif icus &cG. on pagp33. 
See Hamilton (69) under B ryobie prartiosa on page 13. 
Turner ( 146 ) in 1932 reported that cube extract 1:25,000, emulsified in 
2 percent cf oil with a sulfonate emulsifier, killed 86.9 percent of European 
red mite eggs, whereas the check oil killed 89,6 "ercent. 
Heal (73) in 1936 reported field tests made in He*" Jersey for the control 
of the European red mite on apples. Derris was supplied in three forms, a dust 
containing 1 percent of rotenone, a dust containing 0,75 percent, and a finely 
ground root containing 4 percent. Aresket, Areskap, Aresklene, skim milk, and 
soap were used as wetting agents. The most satisfactory- combination consisted 
of 1,25 to 2 pounds of derris root (4 percent. rotenone) and 10 ounces- of Aresket 
or Areskap to 100 gallons of spray. The outstanding feature of this spray, 
beyond its toxicity to the pest, was its compatibility with sulfur and lead 
arsenate deposits on the foliage, the presence of the former precluding the use 
of any oil spray, and the presence of the latter estopping the use of any spray 
containing soap. Two applications spaced from 1 to 2 weeks apart were necessary 
to effect control. A dust made from derris and. containing 1 percent of rotenone 
was valueless. Clay residues on apples at picking time were objectionable. 
When used so as to give equal rotenone content per unit of spray, derris root 
of 4 percent rotenone content gave better kill than did the 1 percent derris 
dust. As wetting agents, Aresket at 10 ounces per 100 gallons and soap at*.'. 
T)ercent were eaual, and both were superior to skim milk at 2 pounds per 100 
gallons. . 
