Spraying for the Control of the Florida 
Red Scale 
W. W. Yothers, Bureau of Entomology, Orlando 
The adult females of this scale are ex¬ 
ceedingly resistant to the effects of the oil 
emulsion insecticides. The usual dilutions 
of oil emulsion do not produce any mor¬ 
tality on them at all. The crawling young, 
recently settled young or first instar and 
males are readily killed by the usual dilu¬ 
tion of the oil sprays. The usual recom¬ 
mendation heretofore for controlling this 
pest has been two sprayings at an inter¬ 
val of a month or six weeks with a spray 
mixture containing i% of oil in the di¬ 
luted material. The first application was 
designed to kill all young stages. The in¬ 
terval of time would then permit the adult 
females present to finish depositing eggs 
when they will die, and all the eggs will 
then have hatched and have developed 
into young scales. The second application 
was then intended to kill these young 
stages. While these recommendations 
were usually followed by beneficial results 
they never produced a mortality that could 
be called entirely satisfactory. A heavy 
infestation of this scale on the trees grow¬ 
ing on the laboratory grounds gave us an 
opportunity to conduct further experi¬ 
ments for its control. 
TESTS WITH I % OIL 
One Application .—July 28, 1921; ex¬ 
amined August 4, 1921. Used 50 gallons 
spray (emulsion made from y 2 Corvus,. 
y 2 Nabob oil). Killed all young stages 
that had begun to form a covering, but 
after turning over more than 500 adult 
females not a single one was observed to 
have been killed. Normal eggs and crawl¬ 
ing young were present. A second exam¬ 
ination of ten leaves made August 15th, 
or eighteen days after the application, 
gave 280 living and 25 dead adult females.. 
Normal eggs and crawling young were 
present in great abundance. 
Two Applications .—July 28 (1%), 
August 16 (1 y%). Emulsion July 28th 
made of J 4 Corvus and Nabob; August 
16th all Nabob. Used 50 gallons of mate¬ 
rial and sprayed the same trees on August 
16th as given under 1% application. Ex¬ 
amined August 24th or eight days after 
application. Recently settled young had 
been killed. On ten leaves there were 228 
living and 166 dead adult females, or 58% 
living. Many crawlers were alive and 
numerous eggs appeared normal. A sec¬ 
ond examination of 25 leaves made Au¬ 
gust 30th, or 14 days after application, 
gave 254 living and 238 dead adult fe¬ 
males or 51.6% living. A third examina¬ 
tion of 10 leaves made September 20th 
gave 151 living and 137 dead adult fe¬ 
males or 52.4% living. There were not 
