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  The CMCD is focused on constantly improving aerial adulticide applications in order to provide the most efficient mosquito control, while reducing non-target impacts. Since 1995, the CMCD has been studying drift and deposition of adulticide sprays. These studies have helped the district to design new spray systems that provide the best possible mosquito control.
The CMCD uses both fixed wing aircraft and helicopters to perform adulticiding spray missions. During March of 2002, one helicopter was fitted with a new air assist spray system that was previously used only on fixed wing aircraft. The air assist spray system uses hydraulic nozzles in conjunction with the excess bleed air that is produced by the aircraft engines. The two create a fine aerosol mist of adulticide. The mist contains insecticide droplets that are primarily 20-40 microns in diameter. The smaller droplets are much more likely to contact an adult mosquito than the larger droplets, and thus this droplet spectrum is more efficient at controlling mosquitoes. In addition, the smaller droplets are less likely to deposit on the ground, therefore reducing non-target impacts.
 The Research Department at the CMCD monitors the drift and deposition of selected aerial adulticide applications. Special monitoring stations are set up down wind, under the flight path of the aircraft. These stations catch adulticide drift in yarn grids that are placed approximately 6' in the air. The ground deposition is monitored with filter paper, which the adulticide lands on as it falls. After chemical analysis is done, the data from these two materials is run through special mathematical calculations that indicate how much adulticide was deposited or drifted over the target area. This information helps the CMCD to understand whether or not small droplets are being produced by the spray system. In addition, actual droplet sizes being produced by the spray system nozzles can be determined with the use of a specially designed wind tunnel and laser system.
During the mosquito season of 2002, the CMCD conducted multiple drift and deposition tests on the new air assist spray system that was fitted on one of the District's helicopters, as well as the air assist systems that have already been in place on the fixed wing aircraft. This data proved that the air assist spray system on the helicopter was more efficient at controlling mosquitoes and maintaining a smaller droplet spectrum than the Beecomist atomizers that are currently used on the other District helicopters. Because the new spray system worked so well, all District helicopters will be converted to the air assist spray system before the summer of 2003.
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