Spraying of Insecticides
On this page you'll learn about the different types of spraying available to deal with mosquitos, as well as when spraying will take place.
Truck mounted mosquito sprayer
Truck spraying to kill adult mosquitoes is an essential part of Miami-Dade County's mosquito control program, and the part that citizens see most often.
The spray trucks apply a fine mist of concentrated insecticide through a method known as Ultra Low Volume application (ULV). The amount of insecticide applied is determined by the speed of the truck. If the truck drives faster, more insecticide is applied; if the truck drives slower, less insecticide is applied.
The mist of insecticide from the sprayer is effective for killing adult mosquitoes approximately 300 feet downwind. Truck spraying is used primarily for localized concentrations of mosquitoes throughout various areas of Miami-Dade County.
When we spray
Peak mosquito activity is at dusk, with mosquito activity continuing into the evening hours. Mosquito control spray trucks usually begin spraying at dusk to coincide with this peak activity, and continue spraying until all complaints have been serviced.
Mosquito spraying is not performed those evenings when there are unfavorable climatic conditions such as high winds, rain or cold temperatures. Spraying under these conditions kills very few mosquitoes.
Spray trucks usually operate five evenings per week, Monday through Friday. Spray operations are extended in instances of severe mosquito annoyance, or when mosquito-transmitted disease occurs. Control of adult mosquitoes using truck-mounted equipment is not 100% effective, as the spray droplets are not uniformly distributed throughout the area, and the droplets provide control for approximately 300 feet downwind.
When we don't spray
Spraying is not performed during the day for several reasons:
- Mosquitoes are not as active during the day as in the evening
- Mosquitoes must be actively flying to obtain effective control
- Beneficial insects, especially honeybees, are active during the daylight hours, and insecticides sprayed can kill them
- People are out during the day, and spraying may cause unneeded exposure to the insecticide
- Traffic congestion would make the operation of a spray truck difficult during business hours
- Thermal currents can cause the insecticide to rise or move in directions not conductive to effective control
Aerial spraying to control adult mosquitoes
Aerial spray operations are conducted during the summer months using a fixed-wing aircraft and our Miami-Dade Mosquito Control helicopter. The majority of the spraying is performed in the southwest area of the County in response to large numbers of salt marsh mosquitoes that migrate into the area from the Everglades National Park, Biscayne National Park and the Florida Keys.
Aerial spraying is highly effective, but costly. We use the aircraft only to spray large areas that have heavy infestations of mosquitoes. Aerial spraying is performed at dusk to coincide with the period of greatest mosquito activity.
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