-59- 
Gesarol AK-20, e proprietary powder containing 20 percent of DDT, was 
• es a spr'ay (without any oil) at 10 pounds to 100 gallons of water, 
but even in double applications it was not so effective as 1 3/4 per- 
cent light-medium or heavy-medium oil spray. A 5-percent DDT dust, 
using li pounds per tree in two applications, one in July and one in 
August, resulted in no improved red scale control when compared with 
thfuntreated check plot. In the past year's field work, cube root 
added to kerosene-DDT spray decreased the longterm effectiveness of 
the spray 5 times in the 6 trials in which the comparison was made. 
This is a highly paradoxical situation since cube root increases many- 
fold the ability of kerosene to kill red scale. It cannot be argued in 
this instance ihat the insecticidal effect of the cube root against 
the relatively unimportant predators and parasites of the red seal® 
ouWghed its effect in increasing the initial kill of , the red scale, 
for the DDT appears to be even more effective against predators and 
parasites and this material was present in all the kerosene sprays.- 
Ebeling (142). 
The addition of IDT to oil sprays produced little or no immediate 
effect, but the residual value against the crawlers was considerable in 
cool weather as compared with that in hot weather.— Baker and Porter (81). 
The value of DDT for citrus insect oontrol is yet to be determine*. 
Although the material is promising for the control of citrus thrips and 
scale insects much more work on a large scale is needed.— Boyoe (95). 
Aspidlotu8 perniclo8U8 Comst., the San Jose soale 
A spray of 4 pounds of 20-peroent DDT per 100 gallons of water applied 
to apple trees did not oontrol this scale on the fruit.— Baseman (203 ). 
Chrysomphalus acnidum (L.), the Florida red soale 
No benefit appeared to result from the addition of DDT to oil sprays. 
—Baker and Porter (81). 
Chrysomphalus dictyospermi (Morg.), the dictyospermum soale 
An emulsion containing about 0.2 percent of DDT, applied four times 
within 5 months, proved highly effective against these scales on about 
50 speoies of orchids. The emulsion was prepared by adding a solution 
of 20 parts by weight of TOT in 60 parts of xylene and 20 parts of Triton 
X-100 to water. Young scales or orawlers are unable to live on any por- 
tion of the plant that has been coated with the spray. All mature soales 
will not be killed by a single application but repetitions of the sprays 
at 3- or 4- week intervals should ultimately eliminate all scales, both 
young and old. Ho injury to the plants occurred.— Cory (119) • 
