Almost everyone has had the unpleasant experience of being bitten by a mosquito. Mosquito bites can cause skin irritation through an allergic reaction to the mosquito's saliva - this is what causes the red bump and itching. But a more serious consequence of some mosquito bites may be transmission of serious diseases and viruses such as malaria, dengue virus, Zika and West Nile virus, which can lead to disabling and potentially deadly effects (such as encephalitis, meningitis and microcephaly).

Not only can mosquitoes carry diseases that afflict humans, but they also can transmit several diseases and parasites that dogs and horses are very susceptible to. These include dog heart worms, eastern equine encephalitis and West Nile virus.

There are about 200 different species of mosquitoes in the United States, which live in specific habitats, exhibit unique behaviors and bite different types of animals. Despite these differences, all mosquitoes share some common traits, such as a four-stage life cycle (egg, larva, pupa, adult).

Different species of mosquitoes prefer different types of standing water in which to lay their eggs. The presence of beneficial predators such as fish and dragonfly nymphs in permanent ponds, lakes and streams help keep these bodies of water relatively free of mosquito larvae. However, portions of marshes, swamps, clogged ditches and temporary pools and puddles are all prolific mosquito breeding sites. Other sites in which some species lay their eggs include:

• tree holes,
• old tires,
• buckets,
• toys,
• potted plant trays and saucers,
• plastic covers or tarpaulins and even
• places as small as bottle caps!

Some of the most annoying and potentially dangerous mosquito species, such as the Asian tiger mosquito, come from these sites.

Knowing the different stages of the mosquito's life will help you prevent mosquitoes around your home and also help you choose the right pesticides for your needs, if you decide to use them. All mosquito species go through four distinct stages during their life cycle:

• Egg - hatches when exposed to water.
• Larva - (plural: larvae) "wriggler" lives in water; molts several times; most species surface to breathe air.
• Pupa - (plural: pupae) "tumbler" does not feed; stage just before emerging as adult.
• Adult - flies short time after emerging and after its body parts have hardened.

The first three stages occur in water, but the adult is an active flying insect. Only the female mosquito bites and feeds on the blood of humans or other animals.

• After she obtains a blood meal, the female mosquito lays the eggs directly on or near water, soil and at the base of some plants in places that may fill with water. The eggs can survive dry conditions for a few months.
• The eggs hatch in water and a mosquito larva or "wriggler" emerges. The length of time to hatch depends on water temperature, food and type of mosquito.
• The larva lives in the water, feeds and develops into the third stage of the life cycle called, a pupa or "tumbler." The pupa also lives in the water but no longer feeds.
• Finally, the mosquito emerges from the pupal case after two days to a week in the pupal stage.
• The life cycle typically takes up two weeks, but depending on conditions, it can range from 4 days to as long as a month.

The adult mosquito emerges onto the water's surface and flies away, ready to begin its lifecycle.

Keep mosquitoes out

To keep mosquitoes outside of your home, you can:

• Install or repair and use window and door screens.
• Close doors, including garage doors. Do not leave doors propped open.
• Use air conditioning when possible.

Control mosquitoes inside your home

Mosquitoes rest in dark, humid places like under sinks, in showers, in closets, under furniture, or in the laundry room. Mosquitoes entering your house from outdoors can start laying eggs indoors. Take the following steps:

• Once a week, empty and scrub, turn over, cover, or throw out any items that hold water, such as vases or flowerpot saucers, to remove mosquito eggs and larvae.
• Use an indoor insecticide if you still have mosquitoes in your home after installing and repairing screens and emptying and scrubbing containers.
• Hire a pest control professional to treat areas inside your home.

About indoor insect spray or fogger

An indoor insect spray or fogger will kill mosquitoes and treat areas where they rest.

• These products work quickly but may need to be reapplied.
• Always follow label directions.
• Using only an indoor insecticide will not keep your home free of mosquitoes.

Remove standing water where mosquitoes lay eggs

• Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like tires, buckets, planters, toys, pools, birdbaths, flowerpot saucers, or trash containers. Mosquitoes lay eggs near water.
• Tightly cover water storage containers (buckets, cisterns, rain barrels) so mosquitoes cannot get inside to lay eggs.
• For containers without lids, use wire mesh with holes smaller than an adult mosquito.
• Fill tree holes to prevent them from filling with water.
• Repair cracks or gaps in your septic tank if you have one. Cover open vent or plumbing pipes. Use wire mesh with holes smaller than an adult mosquito.

Kill mosquito larvae outside your home

• Use larvicides to treat large bodies of water that will not be used for drinking and cannot be covered or dumped out.
• When using larvicides, always follow label instructions.

Kill mosquitoes outside your home

• Use an outdoor adulticide to kill adult mosquitoes in areas where they rest.
• Mosquitoes rest in dark, humid areas like under patio furniture or under the carport or garage.
• When using adulticides, always follow label instructions.

WHAT TO KNOW

• Larvicides are a type of insecticide used to control mosquitoes indoors and outdoors.
• Homeowners and professionals can use larvicides to kill mosquito larvae and pupae before they can grow into biting adult mosquitoes.
• When used according to product label instructions, larvicides do not harm people, pets, or the environment.

Overview

Some larvicides are activated when eaten by the mosquitoes, and some types work when they come into contact with larvae.

Homeowners can use mosquito dunks or bits that contain larvicide. Larvicides can be applied by hand to small bodies of water in the yard and community.

Mosquito control professionals can also apply larvicides. Licensed mosquito control professionals apply Environmental Protection Agency (EPA)-registered larvicides using backpack sprayers, trucks, or airplanes depending on the size of the area being affected. During an outbreak, local government departments and mosquito control districts take the lead for large-scale mosquito control activities.

Forms of larvicides

• Dunks, tablets, bits, pellets, granules, briquettes: These forms of larvicide are also applied to areas where mosquitoes lay eggs.
• Liquids: Liquid larvicide products are applied directly to water using backpack sprayers and truck- or aircraft-mounted sprayers.

Information for homeowners

Areas you can treat with larvicides

Use larvicides where mosquitoes lay eggs to help reduce the number of mosquitoes in an area. Follow the instructions on the label. Do not apply more than directed or reapply more often than instructed.

Mosquitoes lay eggs in items that hold water:

• Buckets and rain barrels
• Fountains
• Gutters or downspouts
• Non-chlorinated swimming pools
• Pool covers that collect water
• Tires
• Tree holes

Use larvicides to treat standing water that

• Will not be used for drinking
• Cannot be covered, dumped, or removed

Hire a pest control professional if preferred

Hire a pest control professional to treat your yard and outdoor areas.

Information for professionals

EPA-registered larvicides have been studied for their effectiveness and safety when used according to label instructions. Public health officials and mosquito control professionals use three types of larvicides: bacterial larvicides, insect growth regulators, and oils and films.

Bacterial larvicides

The following types of larvicides are made from natural substances.

• The bacterium Bacillus thuringiensis subspecies israelensis (Bti) is found in the soil. Bti is toxic to mosquito larvae, blackflies, and fungus gnats.
  • Bti has been used for mosquito control for more than 30 years.
  • Bti does not control biting female mosquitoes.
• The bacterium Saccharopolyspora spinosa is found in soil. It is toxic to mosquitoes, ants, fruit flies, and other insects. Spinosad is a commercial larvicide derived from this bacterium.
• The bacterium Lysinibacillus sphaericus (also known as Bacillus sphaericus) is found in soil. It works well on some mosquito species but does not work on Aedes aegypti.

Insect growth regulators

These types of larvicides prevent mosquito larvae from completing their immature stage, so they do not make it to the adult stage. Methoprene and pyriproxyfen are examples of insect growth regulators.

Oils and films

Licensed mosquito control professions use mineral oils and films to kill mosquito larvae and pupae.

• Mineral oils and films, when applied to water, spread in a thin layer over the surface of the water.
• Mosquito larvae and pupae that breathe at the water's surface drown.

WHAT TO KNOW

• Adulticides are types of insecticides used to kill adult mosquitoes.
• Adulticides may be applied by a mosquito control program, a licensed pest control professional, or as a do-it-yourself application.
• When used according to product label instructions, adulticides do not harm people, pets, or the environment.

Overview

There are many types of mosquitoes. Some are considered a nuisance. They bite people and animals but do not spread germs. Some mosquitoes can spread viruses like West Nile, dengue, or others.

Some adulticides kill adult mosquitoes immediately and some continue to kill mosquitoes over longer periods of time.

Homeowners can use adulticides outdoors where mosquitoes rest. Mosquitoes rest under plants, in dense brush or tall grasses, and on the undersides of leaves on trees and bushes. They can also rest under the eaves on buildings, under decks and porches, and in moist, shady areas.

Mosquito control professionals also apply adulticides. During an outbreak of mosquito-borne disease, local government departments and mosquito control districts take the lead for large-scale mosquito control activities. Depending on the size of the affected area, licensed mosquito control professionals apply Environmental Protection Agency (EPA)-registered adulticides using trucks or airplanes.

Forms of adulticides

• Coils
• Foggers
• Yard sprays or aerosols
• Liquids

Information for homeowners

When using adulticides

• Always follow the product label instructions.
• Do not apply more product than recommended or reapply more often than stated on product label instructions.
• Do not apply outside directly to fruits and vegetables in your garden or inside near food.
• Do not apply to plants in bloom or to plants that bees, butterflies, and other pollinators visit.
• Keep people and pets out of the area you treat until the product has dried, usually about an hour. Remember to follow label instructions.

Hire a pest control professional if preferred

Hire a pest control professional to treat your yard and outdoor areas.

Information for professionals

Local government departments and mosquito control districts use liquid adulticides. One way liquid adulticides can be applied is as an ultra-low volume (ULV) spray. ULV sprayers turn the liquid into very small droplets that float in the air and kill flying mosquitoes on contact. Only small quantities of adulticides are needed to kill adult flying mosquitoes in an area.

Liquid adulticides can also be applied as residual sprays. Liquid is sprayed onto vegetation and buildings and allowed to dry. These treatments focus on sites where mosquitoes are likely to land and rest, exposing them to the adulticide. Residual spraying is a special application that is not often used by local government departments and mosquito control districts. They are more commonly applied by pest control professionals.

Types of adulticides used by professionals

EPA-registered adulticides have been studied for their effectiveness and safety when used according to label instructions. The main types of adulticides available for use in the United States are organophosphates, natural pyrethrins, and synthetic pyrethroids.

Organophosphates

Organophosphates are chemical compounds used to control mosquitoes and plant pests. Organophosphates kill mosquitoes by preventing their nervous systems from working properly. Common organophosphates used by mosquito control professionals in the United States include malathion and naled.

Plant-derived pyrethrins and synthetic pyrethroids

Plant-derived pyrethrins are extracted from some chrysanthemum flowers. Mosquito control professionals use plant-derived pyrethrins, often referred to as pyrethrum, to kill adult mosquitoes using ULV spraying.

Synthetic pyrethroids are similar to natural pyrethrins. Mosquito control professionals use different types of synthetic pyrethroids to kill adult mosquitoes using ULV spraying. Examples of synthetic pyrethroids include permethrin, sumithrin (d-phenothrin), and deltamethrin.

Both plant-derived pyrethrins and synthetic pyrethroids kill mosquitoes by preventing their nervous systems from working properly.

WHAT TO KNOW

• Tree holes can be found in the trunk or branches of a tree.
• Tree holes can easily fill with water.
• They are a perfect place for mosquitoes to lay eggs.
• Fill tree holes to reduce mosquitoes in your yard.

How to fill a tree hole

First, determine if the tree hole holds water. Tree holes that do not hold water may provide nesting sites for birds or other wildlife. They do not need to be filled.

If the tree hole holds water, fill the hole with expanding foam used for home insulation projects. Expandable foam is light weight, seals the hole, keeps it from collecting water, and is flexible enough to move with the tree.

• Look for a product that can fill big gaps and is water resistant.
• Follow directions on the product label when applying.
• You do not need to clean out the tree hole before filling.

When filling a tree hole

• DO NOT fill tree holes with gravel or sand. These materials:
  • Do not prevent water from collecting in the tree.
  • Can become a safety issue if the tree is cut down.
• DO NOT fill tree holes with concrete. Concrete is not flexible, adds weight to the tree, and can damage it.
• DO NOT drill drain holes in the tree. This can damage the tree.

Other yard maintenance tips

In addition to filling tree holes, follow these simple yard maintenance tips to reduce mosquitoes in your yard.

• Once a week, empty and scrub containers with standing water, including empty flowerpots, bird baths, and trash containers. These steps should remove mosquito eggs from the inner walls of the container.
• Drain water from pools when not in use.
• Remove water from tarps used to cover items in the yard.
• Mow your lawn regularly and cut down weeds near your home.
• Keep rain barrels tightly covered or screened.
• Apply larvicide to containers with aquatic plants and to plants that hold water, such as bromeliads.

WHAT TO KNOW

• Mosquitoes can spread germs that make people sick.
• Just one septic tank can produce thousands of mosquitoes.
• Mosquitoes get inside broken or unsealed septic tanks and lay eggs.
• After they hatch and grow, thousands of adult mosquitoes fly out of the broken or cracked septic tank each day.

Mosquitoes and septic tanks

Mosquitoes may be laying eggs inside your septic tank if it is

• Open or unsealed
• Broken with cracks or spaces between the blocks
• Missing a ventilation pipe screen cover

Inspect and repair your septic tank

Check local regulations before repairing a septic tank on your own. You can work with a licensed septic tank installer to

• Seal the septic tank.
• Repair cracks or gaps in the exterior walls of the septic tank using cement or expanding foam used for home insulation projects.
  • Look for a product that is made to fill big gaps and is water resistant.
  • Follow directions on the product label.
• Cover vent or plumbing pipe openings using mesh with holes smaller than a mosquito.
• Fill abandoned or unused septic tanks with dirt or gravel.

WHAT TO KNOW

• Misting systems automatically spray insecticides to control mosquitoes around homes and buildings.
• Misting systems spray insecticides at timed intervals.
• Some systems spray Environmental Protection Agency (EPA)-registered insecticides.
• Using misting systems to routinely apply insecticides can lead to undesired effects.

About misting systems

Misting systems automatically spray insecticides to control mosquitoes around homes and buildings. Homeowners can purchase these systems or install their own systems. Misting systems spray insecticides at timed intervals from a series of nozzles installed along the eaves of a house, fencing, or around landscaped areas.

Misting systems are used to spray EPA-registered insecticides, such as natural pyrethrins and synthetic pyrethroids. Minimum risk insecticides can also be used in misting systems. However, minimum risk insecticides do not require registration with the EPA and have not been evaluated for effectiveness.

Importance of integrated mosquito management

An integrated mosquito management (IMM) approach uses a combination of methods to prevent and control mosquitoes. These methods include conducting mosquito surveillance, removing places where mosquitoes lay eggs, controlling larvae and pupae, killing adult mosquitoes, and monitoring control programs to ensure that mosquito control activities are working. When insecticides are used as part of an IMM approach, communities can be confident that local governments and mosquito control programs are applying insecticides only when necessary.

When mosquito surveillance activities show that adult mosquito populations are increasing or spreading viruses, such as West Nile, professionals may decide to apply insecticides to control mosquitoes. However, misting systems are not a method used by community-based mosquito control programs.

Misting systems do not rely on surveillance data and are set to spray insecticide at timed intervals. Therefore, these systems may operate when mosquitoes are not present.

Concerns about routine use of insecticides

Use of Misting Systems‎

Potential harm to beneficial insects

Misting systems apply insecticides day and night, based on how the user programs the system. Bees, butterflies, and other pollinators may be harmed because misting systems spray insecticides when the insects are active.

Local mosquito control programs only apply insecticides when beneficial insects are not active, for example, early morning or late evening.

Harm to the environment

Misting systems are not regulated by the EPA. Routine spraying can lead to inappropriate application of insecticides, which can negatively impact the environment.

Increased risk of exposure to insecticides

Misting systems may not have safety mechanisms to prevent direct contact with insecticides. For example, a neighbor, landscaper, or children may be unaware of when the system will release insecticide, and people and pets could be exposed unintentionally.

The label on some pyrethrin products includes the word "Caution" because the insecticide may be harmful if inhaled. In addition, mist can coat outdoor furniture and children's toys if the system is not properly maintained and calibrated. This can cause unintentional exposure to insecticides.

Insecticide resistance in mosquitoes

Mosquito control professionals monitor mosquito species and numbers to determine when and where to apply insecticides. Over time and repeated use, insecticide resistance can occur in mosquito populations. Insecticide resistance is an overall reduction in the ability of an insecticide to kill mosquitoes. This means that, when used as directed, a product no longer works, or only partially works.

To delay or prevent insecticide resistance in mosquitoes, IMM programs monitor for resistance. Users of misting systems cannot monitor mosquitoes for insecticide resistance. Only professionals can do this.

No data on effectiveness of misting systems

Local governments and mosquito control professionals do not evaluate or collect data on the effectiveness of misting systems. The use of misting systems is not consistent with sound IMM practices.

An increasing number of households have purchased timed-release outdoor residential misting systems to control mosquitoes and other insects around the home. However, advertisers, the media, and other sources sometimes provide information about misting systems that is difficult to understand or might conflict with other information. This fact sheet page will help consumers:

• decide if residential pesticide misting systems are appropriate for their home
• understand safety precautions about using outdoor misting systems
• find related information on Integrated Pest Management -- using a variety of methods for mosquito control
• understand the role of the EPA and state agencies in regulating misters.

Check your instruction manual or contact the manufacturer if you have questions about how to operate or maintain your home misting system.

What are outdoor residential misting systems?

Outdoor residential misting systems (sometimes called "mosquito misters") are application systems designed to spray pesticides in a fine mist to kill mosquitoes and other insects outdoors. Misting systems include spray nozzles that are mounted around the perimeter of a home in the lawn or landscaping, or on parts of the house or fence. The spray nozzles are connected by tubing to a supply of insecticide. Some misting systems may be turned on at preset intervals using a timer. Others may be turned on using a remote controller, while others may be activated using a switch.

What pesticides are used in the misting systems?

The insecticide products most often used in outdoor residential misting systems contain pyrethrins and permethrin. These products may also contain piperonyl butoxide. To be sure what type of insecticide you are using, check the list of active ingredients on the container label.

Certain minimum risk pesticides may also be used in some misting systems. Although not regulated by EPA, many states do regulate these pesticides. Check with your state agency about any requirements or warnings you need to be aware of before you use the pesticide. EPA has not evaluated the potential risk or effectiveness of these minimal risk chemicals in misting systems.

It is illegal to use a pesticide in a misting system if the pesticide label contains a prohibition against use in these systems.

The Label Is The Law

• Pesticide labels provide instructions about proper handling, use, and application rates of the product, and precautions to protect people and the environment.
• Label directions are derived from scientific testing by manufacturers and evaluation by EPA scientists to ensure that products can be used with minimal risk to people and the environment.
• READ THE LABEL FIRST!

Are residential misting systems effective in controlling insect pests?

EPA, as well as the Centers for Disease Control and Prevention (CDC) and many mosquito control professionals, believe that a combination of approaches generally known as Integrated Pest Management (IPM) is most effective at combating mosquito populations.

Outdoor residential misting systems have not yet been studied sufficiently to document their effectiveness in controlling mosquitoes or other yard and garden pests, nor have they been scientifically proven to control or prevent the spread of West Nile Virus or other diseases.

While pest management begins with you, effective mosquito control is often community-based. Contact your local health department or mosquito abatement district to report severe annoyance or potential mosquito sources.

For pests other than mosquitoes, a combination of pest management practices tailored for the specific pest may offer the best results.

Are residential misting systems safe?

People and pets may be exposed to pesticides used in a residential misting system through direct contact with sprays, by touching plants or other objects in the treated area, or by inhaling small amounts of pesticide remaining in the air. EPA has assessed the human health and environmental risks of the pesticides most commonly used in misting systems. Most of these pesticides last only short periods in the environment, so long-term exposure to humans is not expected. Based on its assessment, using toxicity data and exposure estimates, EPA does not expect risks of concern to humans when these chemicals are used in outdoor residential systems according to labeling specific for use in these systems. However, excessive use or accidents may pose risks. No pesticide should be regarded as 100% risk free.

Since pyrethrins and permethrin are toxic to all insects, they may kill beneficial insects such as honeybees, ladybugs, butterflies and other non-target species. In addition, permethrin is very highly toxic to fish.

Installing and Using Misting Systems

When using a misting system, following a few simple guidelines will minimize potential exposure to people, pets, and the environment.

When Having a System Installed:

• Always use installers and service technicians that comply with the state's license, certification, and registration requirements.
• Make sure that the installer has calibrated the system to apply no more than the maximum daily application rate as specified on the pesticide label.
• Make sure the nozzles are directed to spray toward the target area and away from eating/cooking areas and any water body including swimming pools and fish ponds (some pesticides are toxic to aquatic organisms).
• Placing nozzles less than 10 ft from the ground will reduce chemical drift. Chemical drift may affect other people, animals and surrounding environment not in your yard area.
• Set nozzles to direct mist away from outside air conditioners or other home air intakes.
• Make sure both the reservoir and operating system are securely locked and inaccessible to children at all times to avoid potential poisoning accidents.
• When practical, install wind, rain, and motion sensors to reduce unnecessary pesticide usage and inadvertent application when people or pets are present.

When Using a System:

• Do not apply the pesticide when people, pets, or foods are present.
• Set automatic timers for times when people and pets are unlikely to be sprayed.
• Only use the system when pests are most active. For example, certain varieties of mosquitoes are most active in the early morning and evening hours.
• Avoid using the system during high wind (>10 mph), rainfall, fog, or when outside air temperatures fall below 50 Fahrenheit or other times when insects are generally not active.
• Obtain and READ the pesticide label to know the pesticide precautions and its appropriate use in the system.
• Be aware of the maximum daily rate specified on the product label and how your system operates.
• Be a good neighbor - some neighbors may have sensitivities to the pesticides or object to drift of chemicals onto their property.
• Avoid damage or misuse from a leaking or malfunctioning system - regularly maintain and inspect it.
• Turn the system off when not needed for extended periods of time.

In Case of an Emergency

It is important to understand that improper installation of a misting system, over-exposure to pesticides, or unforeseen incidents can lead to serious injury to you and your family and others, as well as to the environment.

Equipment leaking or not working right?

• Turn off the system immediately and contact your installation company.
• Ask the company about any safety precautions you need to follow.
• Always - keep children and pets away from pesticides and pesticide equipment.

Keep handy for emergencies:

• EPA Registration number of the pesticide used in the misting system
• Phone numbers for:
  • National Poisoning Hotline at (800-222-1222)
  • Your local fire department or emergency responder
  • National Pesticide Information Center at 800-858-7378
  • Your service technician

Pyrethroids are synthetic chemical insecticides that act in a similar manner to pyrethrins, which are derived from chrysanthemum flowers. Pyrethroids are widely used for controlling various insects. Permethrin, resmethrin, and d-phenothrin (Sumithrin®) are synthetic pyrethroids commonly used in mosquito control programs to kill adult mosquitoes.

• Permethrin has been registered by the EPA since 1979. It is currently registered and sold in a number of products such as residential indoor and outdoor insect foggers and sprays, treated clothing, flea products for dogs, termite treatments, agricultural and livestock products, and mosquito abatement products. It is also regulated by the Food and Drug Administration as a treatment of head lice and scabies. Permethrin is the most widely used mosquito adulticide in the U.S. and is used to treat 9 to 10 million acres annually (out of 32-39 million acres treated with a mosquito adulticide). Permethrin’s widespread use can be attributed to its low cost, high effectiveness, low incidence of pest resistance, and broad labeling.

• Resmethrin has been registered by the EPA since 1967. It is currently registered for use only in public health and vector control programs to control adult mosquitos, biting and non-biting midges and blackflies. Because of its toxicity to fish, resmethrin is a Restricted Use Pesticide that is available for use only by certified pesticide applicators or persons under their direct supervision. The resmethrin registrants voluntarily canceled all of the resmethrin products. After December 31, 2015, resmethrin registrants will no longer be able to sell and distribute resmethrin products. However, user will be able to continue using any product they have purchased.

• D-phenothrin (Sumithrin®) has been registered by the EPA since 1976 for use to control adult mosquitos and other nuisance insects indoors and outdoors in residential yards and public recreational areas. Use sites include in and around residential/domestic dwellings, commercial and industrial buildings, transportation vehicles, recreation areas, animal quarters, direct animal treatment (dogs). While there are no direct applications to food crops, d-phenothrin labels allow for applications to control mosquitoes over agricultural as well as non-agricultural areas.

How are Synthetic Pyrethroids Used in Adult Mosquito Control?

Most pyrethroid mosquito control products can be applied only by public health officials and trained personnel of mosquito control districts. Mosquito control professionals apply pyrethroids as an ultra low volume (ULV) spray. ULV sprayers dispense very fine aerosol droplets that stay aloft and kill adult mosquitoes on contact. Pyrethroids used in mosquito control are typically mixed with a synergist compound, such as piperonyl butoxide, which enhances the effectiveness of the active ingredient. The product is often diluted in water or oil and applied at rates less than 1/100th of a pound of active ingredient or less than 4 fluid ounces of mixed formulation per acre.

Do Pyrethroids Pose Risks to Human Health?

We have conducted human health risk assessments for all labeled uses of pyrethroids. Based on the results of these assessments and any required label changes, pyrethroids can be used for public health mosquito control programs without posing unreasonable risks to human health when applied according to the label. At high exposure levels, such as those resulting from accidents or spills, pyrethroids can affect the nervous system.

Do Pyrethroids Pose Risks to Wildlife or the Environment?

When applied according to label directions, pyrethroids used in mosquito control programs do not pose unreasonable risks to wildlife or the environment. Pyrethroids are low in toxicity to mammals and are practically nontoxic to birds. However, pyrethroids are toxic to fish and to bees. Products for uses other than mosquito control may be subject to buffer zones to protect water bodies. There also is language on product labels to reduce risks to pollinators. Always read the product label and follow its directions carefully when using any pesticide.

What is The Current Regulatory Status of Pyrethroids?

We are currently reevaluating all pyrethrins, pyrethroids and synergists through registration review. Registration review is our program for systematically reviewing all registered pesticides every 15 years to make sure that every pesticide can still perform its intended function without unreasonable adverse effects on human health or the environment.

As a result of the Food Quality Protection Act, EPA must consider the cumulative risks of pesticides that, like the pyrethroids and pyrethrins, share a common mechanism of toxicity. In November 2011, we completed a cumulative risk assessment for the pyrethroids/pyrethrins and identified no cumulative risks of concern.

Using the right insect repellent and other preventive actions can discourage mosquitoes, ticks and other biting insects from landing on you. Here are tips for other preventive actions you can take against mosquitoes.

Remove Mosquito Habitats

• Eliminate standing water in rain gutters, old tires, buckets, plastic covers, toys, or any other container where mosquitoes can breed.
• Empty and change the water in bird baths, fountains, wading pools, rain barrels, and potted plant trays at least once a week to destroy potential mosquito habitats.
• Drain or fill temporary pools of water with dirt.
• Keep swimming pool water treated and circulating.

Use Appropriate Pesticides

• Control mosquito larvae using the appropriate methods for the habitat
• Control adult mosquitoes using insecticides.

Use Structural Barriers

• Cover all gaps in walls, doors, and windows to prevent mosquitoes from entering.
• Make sure window and door screens are in good working order.
• Completely cover baby carriers and beds with netting.

Avoid Getting Bitten

• Keep mosquitoes away from exposed skin by wearing long-sleeved shirts, long pants, and socks.
• Tuck shirts into pants and pants into socks to cover gaps in your clothing where mosquitoes can get to your skin.
• Stay indoors when possible, especially if there is a mosquito-borne disease warning in effect.
• Use EPA-registered mosquito repellents when necessary and follow label directions and precautions closely.
• Use head nets, long sleeves and long pants if you venture into areas with high mosquito populations, such as salt marshes.
• Replace your outdoor lights with yellow "bug" lights, which tend to attract fewer mosquitoes than ordinary lights. The yellow lights are NOT repellents, however.