Frequently Asked Questions 

What are mosquito adulticides?

Adulticides are insecticides applied to kill adults mosquitoes. The most commonly used adulticides include Anvil (sumithrin and piperonyl butoxide), malathion, and Scourge (resmethrin and piperonyl butoxide). Other insecticides, such as permethrin, are used to control adult mosquitoes around homes and out buildings.

What is adulticiding?

Adulticiding is the apllication of insecticides to control mosquito adults. This is usually the least efficient mosquito control technique, however, it is an important part of an effective mosquito management program if it is based on mosquito surveillance information.

How does mosquito adulticiding work?

The idea behind mosquito adulticiding to release the insecticide in as many very fine droplets as possible. Adult mosquitoes are killed when they come into contact with one of these droplets as they are flying. Very fine droplets are used because the more droplets there are and the longer the droplets stay in the air, the better the chances are that a droplet will come in contact with a mosquito.

In what form are mosquito adulticides used?

Adulticides are most commonly applied as very fine droplets to quickly kill adult mosquitoes present in a given area. Longer-lasting adulticides also may be applied to known adult resting areas to provide longer term control. Such treatments are referred to as barrier treatments.

Where are adulticides used to kill mosquitoes?

Mosquito adulticides usually are applied as a last resort in areas where public health officials have decided that the healths risks from West Nile virus or other mosquito borne illness outweigh the risk from exposure to the insecticide.

When will adulticides be used for mosquito control?

Mosquito adulticides are usually applied as a last resort when public health officials have decided that the healths risks from West Nile virus or other mosquito borne illness outweigh the risk from exposure to the insecticide. The public is notified when this decision is made.

How are mosquito adulticides applied?

Mosquito adulticides are most often applied as very fine droplets that are intended to come into contact and kill flying mosquitoes. This is often called fogging. Longer-lasting adulticides also may be applied to known adult resting areas to provide longer term control. Such treatments are referred to as barrier treatments.

What are barrier treatments for control of mosquito adults?

Barrier treatments are intended to make a chemical barrier between a mosquito breeding site and an inhabited area. Typically, these are applied by homeowners with handheld equipment to vegetation and other mosquito resting areas around the edges of their property (see www.ext.colostate.edu/pubs/insect/05526.html for details). The insecticides used for barrier treatments last much longer in the environment that those applied by fogging. Public or organized mosquito control program generally do not use barrier treatments as one of their main control strategies.

Why is adulticiding often called fogging?

Adulticides used to be applied with thermal applicators that released a smoke-insecticide mixture that looked like fog. While these applicators are still in limited use today, most adulticides are applied with truck or aircraft mounted equipment, using small amounts of insecticides mixed in a small amount of water or other carrier. The correct name for these applications is ultra low volume (ULV), but the term fogging is still commonly used.

Are adulticides any better at killing mosquitoes than pesticides that attack larval mosquitoes (larvicides)?

The use of mosquito larvicides generally is considered preferable to the use of adulticides for several reasons. (1) Use of mosquito larvicides prevents the appearance of the blood feeding adults. (2) Mosquito larvicides can provide up to a month of control, rather than the few hours provided by fogging with adulticides. (3) The commonly used mosquito larvicides are less toxic than the adulticides and are applied in such a way that there is much less human exposure. (4) Mosquito larvicides generally are applied to smaller areas than are adulticides.

If we use adulticides for mosquito control now, does that mean we do not need to use mosquito larvicides?

Effective mosquito control programs emphasis larval control. Mosquito larvicides are used first and adulticides are used only as a last resort. The use of larvicides minimizes the need for adult control, but may not eliminate it altogether. Adult mosquitoes are strong fliers and may move several miles to feed. Also, certain breeding areas may be inaccessible or may be untreatable for environmental or economic reasons.

Am I likely to be exposed to mosquito adulticides?

Mosquito adulticides are used only in certain high risk areas. If adulticides have been used in your community in the past it is likely that they will be used again. Additional communities may be treated during a bad mosquito year or if West Nile virus or other mosquito borne illnesses are active. Precautions to minimize your exposure to mosquito adulticides if it becomes necessary to treat include:

• Keep in mind that these insecticides are short lived and most of the risk occurs during the application and for an hour or so afterwards.
• Remain inside during the spraying.
• Keep children inside during spraying and for about one hour after spraying.
• Close your windows and doors. If you use an air conditioner turn it off or set it to recirculate indoor air.
• Avoid eye contact with the spray if you are outside during spraying, and rinse your eyes with water or eye drops if they do come in contact with the spray.
• Wash skin surfaces that come into contact with the insecticide.
• Rinse fruits and vegetables from your garden thoroughly with water before cooking or eating.
• Cover outdoor furniture and play equipment before the application, or wash them with soap and water afterwards.
• Bring in laundry and toys before spraying or wash them afterwards.
• Bring pets inside and cover ornamental fish ponds during the application.
• Consult your doctor if you think your health was affected by the spraying.

What problems could I have if I am exposed to mosquito adulticides?

The known health threats associated with commonly used mosquito adulticides are considered to be less serious than those posed by West Nile virus and other mosquito borne illnesses. The Environmental Protection Agency has a website with toxicology information on the pesticides used to control mosquitoes, www.epa.gov/pesticides/factsheets/skeeters.htm.

What should I do if I am exposed to mosquito adulticides?

If you are concerned that you are suffering adverse health effects from exposure to mosquito adulticides, contact your local health department to find out what products were used. After you know what you were exposed to you may consult with your doctor or contact the Rocky Mountain Poison and Drug Center (1-800-332-3073) for further information.

Are mosquito adulticides available to the public for home use?

Yes, a number of insecticides available to the public are labeled for mosquito control. Be sure to read, understand and follow all label instructions and precautions.

What is Anvil insecticide?

Anvil insecticide is used to fog for adult mosquitoes. It contains sumithrin and piperonyl butoxide, which is a synergist (makes sumithrin more toxic to the mosquitoes). The Environmental Protection Agency has a website with toxicology information on the pesticides used to control mosquitoes, www.epa.gov/pesticides/factsheets/skeeters.htm.

What is malathion?

Malathion is an insecticide that has been used for many years to fog for mosquito adults, as well as to control a number of other pest insects. The Environmental Protection Agency has a website with toxicology information on the pesticides used to control mosquitoes, www.epa.gov/pesticides/factsheets/skeeters.htm.

Can malathion be used as a larvicide?

Under certain limited conditions some formulations of malathion may be used as a larvicide. It may be applied to intermittently flooded areas, stagnant water, and temporary rain pools. Malathion may not be applied to any fish-bearing waters.

Updated Monday, July 28, 2003.

This information is provided by CSU Cooperative Extension

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