-81- 
It was shown ohemioally and by use of the red scale that rote- 
none and derris- containing preparations decompose when incorporated 
into spray materials. All these spray materials should be protected 
against the adverse effects of atmospheric oxidation, sunlight, and 
high temperatures. The toxioants used are drastically short-lived 
under field conditions*— Gunther (249) • 
In a chemical study of solubilizers for petroleum oils and ex- 
tracts of rot enone-b earing roots it was remarked that toxicologioal 
evidence points to the fact that certain heterogenous compositions 
are effective for control of the red scale and black scale, possibly 
because the active constituents of the extract are in solution*— 
Kagy and Boyce (334 ) • 
Extensive tests in several southern California citrus districts 
showed that rotenone materials added to oil sprays gave a high kill* 
In a 5-year spraying program on a large commercial orchard, applica- 
tions of rotenone and light medium oil in the spring and again in 
the fall kept the trees comparatively free of the red scale, and e- 
liminated all other pest control problems except thrips* Kerosene 
or light oil which give 70 to 87 percent mortality will, upon the 
addition of derris or cube products, cause 96 percent mortality* 
Heavier oils which are more efficient than light oils may also be 
increased in effectiveness by rotenone* Rotenone is equally effec- 
tive whether in complete solution or in suspension in the spray* A 
minimum of 25 grams of derris or cube resins per 100 gallons of 
finished spray material appears to be necess8ry*~McBeth and Allison 
(373 . 374). 
Rotenone incorporated in oil may make possible the more effec- 
tive use of oils of even lighter grades than those used in 1941* 
The need for improvements in control of the red scale where the re- 
sistant strain oocurs has been urgent, and up to 1941 there was con- 
siderable promise in the kerosene-rotenone spray*— Quayle (482 , p* 9; 
483). 
In field tests against the California red scale, the addition 
of oube extract or niootine to mineral-oil emulsions increased their 
effectiveness to a marked extent, particularly against scales on wood 
where oil alone was less effective. Extracts of rotenone-contain- 
ing plants were more toxic in oil sprays than nicotine, the most ef- 
fective combination having been cube resins in a soluble oil. In 
field trials the percentage mortalities of adults on grey wood and 
on fruit were increased from 36 to 76 and from 82 to 96, respectively, 
by the addition of cube resins to the spray* An increasing pro- 
portion of the total spray mixture deposited on the wood became in- 
secticidally active as the deposits increased*— U* S* Bureau of Ento- 
mology and Plant Quarantine (613, p. 7j 619, p. 9; 623, p. 9). 
