Aerial Adulticide FAQ

Why is aerial spraying taking place? 

The District conducts aerial spraying based on surveillance indicating high mosquito activity or disease transmission within an area. Aerial spraying can help by reducing the number of infected adult mosquitoes which will reduce the risk of disease transmission to people. In addition, mosquitoes are exhibiting resistance to pyrethrins/pyrethoids, so utilizing aerial applications of organophosphate products allows us to effectively manage these resistant populations. For more information on our surveillance program please click here: TMAD Surveillance

What types of insecticides are used in aerial applications? 

Adult mosquito control is always a last resort. The District strives to control mosquitoes in the larval stage before they disperse as adults; however, this is not always possible. When surveillance indicates high mosquito populations and/or disease activity, then ground and/or aerial adulticiding may be utilized.

Aerial applications use EPA-approved products containing one of the following active ingredients:

  • Pyrethrin
  • Piperonyl Butoxide (PBO)
  • Naled (an organophosphate)

Pyrethrin/PBO is applied currently at a rate of 0.64 oz/acre; Naled is applied currently at a rate of 0.75 oz/acre.  (That is roughly 1 1/2 tablespoons over a football field.) This is a very small amount of product applied 300' in the air. The microscopic droplets released float in the air column and dissapate before ever reaching the ground, there is no safety nor health concerns for people or pets.

When are mosquito control applications made? 

 Generally, applications are made early in the morning, evening or nighttime hours when mosquito species are most active. This is also when the winds are calm and the most effective insecticide application can be made.

How can I find out if spraying is taking place in my area? 

Interested residents can be notified of our activities and review maps detailing where our adult control activities are taking place. There are 3 notification options:

When do spraying notifications get posted? 

Generally, the notifications will be posted 24 to 48 hours in advance of applications. Treatments may be canceled and rescheduled due to weather conditions or other unforeseen reasons.

Why can I see and hear the plane if I am not within the treatment area? 

The plane is equipped with specialized tracking equipment which is sensitive to current weather conditions. The equipment measures wind speed, direction, humidity, and temperature. The equipment is able to determine what flight adjustments the plane needs to make, to place the spray in the targeted area. The droplets being released are so small that the equipment must make calculations even for the smallest amount of wind. This means that often times the weather conditions may require the plane to fly offset from the target area. Remember, these microscopic droplets don't hit the ground, mosquitoes don't live on the ground. The droplets float in the air column in the target area until they dissipate.

Is it safe to be outside when the applications are made? 

The applications do not pose a significant risk to you or your family, there are no precautions that need to be taken. People who suffer from chemical sensitivity may want to remain indoors and keep windows and doors closed during the application. The material degrades rapidly in the environment and should not interfere with normal outside activities.

What steps should I take to reduce exposure during spraying? 

There is no need for individuals to take any other special precautionary measures during mosquito control spraying. However, people with chemical sensitivity may want to remain indoors and take the following steps:

  • Close windows and doors. Turn off any window mounted AC. Generally, there is no material left in the air 15-minutes after the application is made.
Can pets go outside during spraying? 

The materials used for controlling mosquitoes do not pose any risk to animals when used in accordance with the pesticide label. However, if you want to reduce your pet‘s exposure, keep them inside during the application. 

Should I turn off my air conditioner if spraying is scheduled in my area? 

There is no need for any special precautionary measures during mosquito control spraying. However, as mentioned above, people who suffer from chemical sensitivity may want to close doors and windows and turn off any window mounted AC units. Since a central air-conditioning unit does not pull in outside air (recirculates interior air), there is no need to turn these units off at all.

Where can I get additional information regarding specific insecticides? 

The National Pesticide Information Center (NPIC) provides insecticide information and questions about the impact of insecticide use on human health. NPIC is cooperatively sponsored by Oregon State University and the U.S. Environmental Protection Agency. NPIC can be reached online or toll-free: 1-800-858-7378.

Questions concerning specific insecticides can be directed to the U.S. Environmental Protection Agency, as this agency has the responsibility for registration of insecticides. Many topics are also addressed on the EPA's Mosquito Control Page.