Behe 
For example, 3 pounds of DDT in 3 gallons of solution with a particle 
size of 40 microns released across a 100-foot front in a 3-mp.h. wind 
will leave a deposit of about 1 pound per acre across a 300-foot swath. 
If 1 pound of DDT in 1 gallon of solution is released across the 100- 
foot front in the same wind and the particle size is raised to 70 microns, 
the same deposit will be obtained across a 100-foot swath. 
When the proper particle size has been selected, the aerosol machine 
should be set to produce this particle size according to the directions 
of the manufacturer. 
Sometimes temporary control of flying insects is desired. The 
optimum particle size for this type of treatment depends upon the kind 
of insect, and not upon the deposit. For adult yellow-fever mosquitoes 
it is about 15 microns, and for house flies about 22 microns. 
Dosage 
The dosage depends on the deposit per acre of insecticide required 
to control the insect. It is measured by the amount applied per 100 
feet of front, and varies with the swath width. Values are based on the 
premise that 25 percent of the insecticide deposits in the first swath. 
Application to successive swaths results in overdrift, which increases 
the deposit by 10 to 20 percent in each swath. Ina large field the 
wastage due to overdrift is thus reduced to that from the last few 
swaths. For swaths less than 300 feet wide the dosage can be reduced 
by about 20 percent, and for swaths 300 to 500 feet wide by about 10 
percent in each successive swath until a 50-percent reduction is reached. 
This reduced dosage should then be repeated to the end of the plot. 
The amount of insecticide required per 100 feet can be released by 
two methods. The total amount required on a front can be applied by 
moving the aerosol generator back and forth across this front until the 
material is exhausted. The second method is to calibrate the output of 
the generator and then calculate the proper speed to move across the 
front to give the desired dosage. As an example of the second method, 
if it is desired to release 2 gallons per 100 feet from a generator with 
an output of 40 gallons per hour, the output per minute will be 2/3 
gallon. Since 1 mp.h. is equivalent to 88 feet per minute, the speed 
of movement will be 
100 2/352 Oy eDehe 
38 x 5 374 Mep 
Formulations 
To prevent rapid evaporation it is desirable that at least one-fourth 
of the aerosol solution be a nonvolatile liquid. Best results have been 
obtained with a very concentrated solution. A much-used formula is 5 to 
7 1/2 pounds of DDT dissolved in 2 gallons of benzene or xylene plus 
3 gallons of SAE 10W motor oil or an agricultural oil. An agricultural 
