Mosquito Control

More PRI Pest Management Bulletins

Getting bitten by mosquitoes?

Understanding the mosquito life cycle is the key to avoiding bites and reducing populations around your home. When traveling in areas where mosquito-borne diseases are a concern, take measures to limit your exposure and consider using an insect repellent. Low impact approaches and non-chemical measures that target mosquito larvae are highlighted in this Pest Management Bulletin.


See PRI’s Top-Ten List for Keeping Pests Out and Kids Safe. Use PRI’s tool, PestSmart, to find low-hazard pesticide products.

 

 

 

Preventing and Managing Mosquito Invasions

Insect Mosquito Mosquitoes flying around your home can cause those itchy red bumps, and can potentially transmit disease. Your vector control district actively conducts large-scale mosquito management, but everyone can help prevent the spread of malaria, West Nile Virus and other mosquito-borne health threats. The goal is to remove breeding grounds and eliminate mosquito larvae to keep population levels low.

Life Cycle

The most effective control methods target the larval stage of the mosquito life cycle. In the United States there are nearly 200 species of mosquitoes, each with its own preferred habitat for laying eggs. Culex mosquitoes, a common species found in North America, will lay hundreds of eggs that stick together to form a raft on the surface of still water; some species will lay only a single egg. Floodwater mosquito species prefer moist soil where their eggs can patiently wait for water to pool, months or even years later.  Mosquito eggs will hatch in water within 48 hours, and the larvae transform into airborne adults within two weeks. Female mosquitoes need protein from mammalian blood to breed and are the ones responsible for all those painful bites. Stop the cycle and protect yourself from these bothersome feeders with the low impact approaches outlined in the following sections.

Common Mosquito Species

Name Preferred Habitat Hours of Activity Range
Aedes Temporary floodwater pools, fresh and brackish marshes, containers. All hours Worldwide distribution, including extreme northern latitudes
Anopheles Fresh- or salt-water marshes, swamps, grassy ditches, the edges of streams and rivers, and small, temporary rain pools. Dawn, dusk, at night Temperate, subtropical and tropical areas worldwide
Culex Freshwater pools, ditches, ponds, and sewage treatment plants. Dusk, daytime Tropics to cool temperate regions worldwide
Mansonia Aquatic plants, water lettuce, and cattails. Sunset Tropics worldwide
Psorophora Temporary floodwaters, woodland pools, roadside ditches, and pastures. Early evening, daytime in shade Tropics and warmer temperate regions of North and South America
Wyeomyia Bromeliad habitats and pitcher plants. Daytime Central and South America, the Caribbean and Florida
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Read on for information on low-impact methods for managing mosquito infestations. Also included is a comparison of the active ingredients commonly used in mosquito insecticides and repellents.

Interested in finding out more about specific mosquito repellent and insecticide products? The Pest Smart app is now available in the iTunes Store. Conveniently access pesticide data on your iPhone and iPad while on the job, in the store, and at home.

  • Search by product name or registration number.
  • Search by pest to find pesticide products that target common household and garden pests like ants, fleas, cockroaches, lawn weeds and aphids.
  • Quickly verify the eligibility of a pesticide product for use in the LEED v4-certified Integrated Pest Management (IPM) program.
  • Compare products and find least-toxic alternatives to streamline decision-making.
  • Link to PRI’s Pest Management Bulletins to learn about low-impact methods of pest control that minimize pesticide use and exposure.

Low Impact Approaches

The control measures outlined below are best used in combination to disrupt the mosquito life cycle. By removing breeding sites and using window screens, you can potentially reduce the number of mosquitoes in and around your home and also limit your exposure to them.

Remove Habitat

The best way to avoid mosquito bites is to locate and remove standing water where mosquitoes can lay eggs. Larvae are usually found on the surface of stagnant water. While it is unlikely that you can eliminate every possible area where water pools, you can minimize popular mosquito habitats.

  • Remove any items located outdoors that can collect water, including buckets, old tires, bottles, wheelbarrows, and cans. For inflatable or kiddie pools, change the water frequently, drain or cover when not in use.

  • Keep swimming pools circulating and chlorinated at all times.
  • Avoid creating small puddles with excessive irrigation. Check to make sure plants have proper drainage and maintain vegetation to reduce the number of places where adult mosquito can take shelter.
  • If your home has a septic tank, test it for proper functioning and make sure that no puddles form in the drain field.
  • Remove debris from rain gutters regularly and keep street gutters clear to prevent water runoff from pooling. Remember to check items stored outdoors, like plastic tarps, as well as tree stumps for standing water.

Use Natural Enemies

Consider using mosquitofish in areas where standing water cannot be drained in natural pools and ponds. Several species of birds, bats, fish, spiders and predatory insects also eat mosquitoes and will complement other control methods.

The mosquito-eating fish, Gambusia affinis, is an important control agent for immature mosquitoes. It feeds on the larvae and is most effective in ornamental ponds or other man-made bodies of water that do not connect with natural waterways. Never release mosquitofish into streams, ponds or lakes as they can become invasive. Some vector control districts offer mosquito fish free of charge. Contact your vector control district for more information. Goldfish and koi will also eat mosquito larvae.

 

Seal Them Out

Exclude mosquitoes from your home by keeping doors and windows tightly shut or add screens with insect-proof netting.  Keeping fine mesh screens in good repair will maintain an effective barrier. For mosquitoes that do make it inside, try to kill them with an old-fashioned fly swatter.

 

Minimize Exposure

Removing mosquito habitat from your yard may not be enough to eliminate all mosquitoes.

 

  • Prevent bites by avoiding the outdoors when mosquito activity is at its greatest, often at dawn, early evening and dusk.
  • If staying inside is not an option, wear long sleeves and pants or a hat with netting to minimize exposed skin and avoid areas like swamps, marshes, and slow moving streams where mosquitoes thrive.
  • Avoid shady shots and places sheltered from the wind. Biting is less of a problem in sunny, brightly lit areas and a breeze will make it harder for mosquitoes to find you.
  • Turn on a fan, moving air will keep mosquitoes and other weak flyers away. This works best in a relatively small area where you can set up a fan or two to create good air flow.
  • If there are more mosquitoes in the house than you can kill with a fly swatter, cover beds with netting, especially cribs.

Mosquito Control Pesticides

Potential Consequences of Using Mosquito Control Pesticides

Recognize that when you use mosquito-control pesticides, you should be ready to deal with these potential consequences:

  • Pesticides applied to skin may cause skin irritation. In some individuals, hypersensitivity and/or psychological effects have been noted from exposure to DEET.  Avoid frequent or heavy use of insect repellents, and wash the skin with soap and warm water after use.
  • Insect repellent formulations can be irritating to some and in high concentrations can damage clothing or plastics.
  • Use of aerosol sprays or foggers guarantees exposure to the pesticidal active ingredient, through inhalation of the spray droplets and contamination of exposed surfaces. See US EPA’s page on foggers.

Precautions to Take When Using Mosquito Control Products

If you determine that pesticides are necessary, take these precautionary steps to reduce the potential for adverse effects:

  • Never spray repellents directly onto your face; apply first onto your hands, then apply the product lightly onto your face and head. Better yet, apply the repellent to a hat and wear the hat.
  • Use repellents sparingly; applying heavier doses does not increase protection. Repellents do not kill mosquitoes; they discourage them from attacking treated areas. Effectiveness and duration of repellency vary considerably, with most lasting for four hours or less.
  • Apply repellents only to clothing and exposed skin; never use underneath clothing. Do not apply on cuts or irritated skin.
  • Never apply oil of lemon eucalyptus on children under three; it has not been tested on children of this age. Do not allow children to handle mosquito-control products.
  • Always read and follow the label instructions on the pesticide product. The label is the law.

 

Mosquito-Control Pesticides

There are many mosquito-control products sold to reduce mosquito populations at home, including liquid, granular and powder formulations. When using these chemical products, take precautions to minimize human, pet, and environmental exposure. The information below will help you understand the risks associated with the active ingredients in these products.

Aerosol Sprays, Foggers and Outdoor Misting Systems

Use of aerosol sprays, foggers and misting systems is not recommended, due to the high probability of harm during the application from inhaling the pesticides and touching the residues they leave behind. People and pets may be exposed to pesticides through direct contact with spray droplets, contact with objects in the treatment area on which residues have landed, or inhalation of aerosolized pesticide in the air.

Outdoor sprays can drift away and pose a risk to non-target wildlife such as fish, honey bees, ladybugs, and butterflies. These systems provide only temporary relief from mosquitoes, and widespread use can lead to mosquito resistance.

See US EPA’s page on outdoor residential misting systems.


Plugins like these put pesticides into the air, causing unnecessary inhalation exposure.

Mosquito Insecticides

Type of Active Ingredient Representative Chemicals* Hazards Formulation
*For groups of active ingredients of the same type.
Bacillus thuringiensis Bacillus thuringiensis Israelensis (Bti)
Bacillus sphaericus 2362, Serotype H5a5b
Practically nontoxic to humans, pets, fish and wildlife. Both strains occur naturally in the environment and are highly selective toxins that only target mosquito larvae and that of a few related flies. Granular, Briquette, Solution, Dust
Botanicals Linalool
Neem oil
Nepeta cataria oil (catnip)
Oil of cedar wood
Phenylethyl propionate
Several naturally occurring substances are available in products sold for mosquito control, including neem and linalool (from mint and citrus plants). Contamination of surfaces with these common components of foods is not hazardous, but inhalation of the spray can be problematic. Spray, Solution
Insect Growth Regulators
(IGR)
Pyriproxyfen
Methoprene
Diflubenzuron
Very low acute and longer-term toxicity to humans. High toxicity to aquatic invertebrates. Diflubenzuron affects the hemoglobin of animals in studies. P-chloroaniline (PCA), a metabolite of diflubenzuron, is classified as a probable human carcinogen. Most products with IGRs also contain an insecticide, usually a pyrethroid. Aerosol, Solution, Powder, Pelleted/tableted, Impregnated materials
Ketones Dihydro-5-pentyl-2(3H)-furanone
Dihydro-5-heptyl-2(3H)-furanone
Poses a low acute toxicity risk to humans and pets. Slightly toxic to freshwater invertebrates. Granular, Solution
Polyalkyloxy Compounds Butoxy poly propylene glycol (BPG)
Poly (oxy-1,2-ethanediyl), alpha-isooctadecyl-omega-hydroxy
Low acute toxicity. BPG is never used as the sole active ingredient in a product, but is often used with pyrethrins, piperonyl butoxide, and pyrethroids. Solution, Spray
Spinosad Low acute toxicity for humans and pets, and not likely to cause cancer or other long-term harm. Highly toxic to bees. Solution, Powder, Granular, Briquette
Fipronil Moderately acutely toxic by ingestion, but not absorbed substantially through the skin. Toxic to the nervous system. Classified as a possible carcinogen by US EPA. In pure form, high acute toxicity to aquatic life and to birds; acute toxicity is less of a concern in dilute products. Pelleted, Powder, Solutions, Granular, Impregnated materials
Avermectin High acute toxicity in pure form, but at low concentrations it has low acute toxicity. Toxic to the nervous system and to the developing fetus at very low doses. Not absorbed through the skin to any great extent. Highly toxic to fish and aquatic invertebrates. Ready-to-use solution
N-Methyl carbamates Carbaryl
Propoxur
High acute toxicity to humans at low concentrations. Toxic to the nervous system, especially for children. Highly toxic to aquatic life. Aerosol, Granular, Solution, Impregnated materials
Neonicotinoids Acetamiprid
Dinotefuran
Imidacloprid
Thiamethoxam
Moderate acute toxicity to humans and absorbed through the skin to some extent. Toxic to the nervous system. Imidacloprid has been shown to reduce sperm counts in laboratory animals with long-term exposure. Most are highly toxic to aquatic invertebrates and bees. Acetamiprid has a ranking of hazard tier two, it poses a low acute toxicity risk to humans and is only moderately toxic to bees. Granular, Solution, Aerosol, Impregnated materials
Organophosphates Chlorpyrifos
DDVP
Malathion
Naled
Propetamphos
Temephos
High acute toxicity to humans at low concentrations. Toxic to the nervous system, especially for children. Highly toxic to aquatic life. Aerosol, Solution, Granular, Impregnated materials
Pyrethroids Allethrin
Bioallethrin
Cyhalothrin
Cypermethrin
Deltamethrin
Esfenvalerate
Ethofenprox
Metofluthrin
Permethrin
Tetramethrin
Moderate acute ingestion and inhalation toxicity. Sensitizer, causing allergic reactions and asthma in some people. Toxic to the nervous system. Highly toxic to aquatic invertebrates and bees. US EPA has classified ethofenprox, metofluthrin and permethrin as likely carcinogens, and cypermethrin, tetramethrin and bioallethrin as possible carcinogens. Most products containing pyrethroids also contain a synergist that increases the insecticidal activity of the pyrethroid. Typical synergists include piperonyl butoxide (PBO) and N-octyl bicycloheptene dicarboximide. US EPA considers both of these synergists possible carcinogens. Solution, Granular, Aerosol, Impregnated materials

Other Products

  • The effectiveness of most other products marketed to repel mosquitoes differs greatly.  Burning citronella candles or mosquito coils containing allethrin are for outdoor use only and work best when there is little air movement.
  • Plant oils such as pine, spearmint, geranium and neem will help deter mosquitoes.
  • You can trap mosquitoes with products that release carbon dioxide, but these capture only a small proportion of the insects drawn in. Many of the insects that are killed by electric bug zappers prey on mosquitoes, making these devices counterproductive for mosquito control.
  • Clip-on metofluthrin dispensers can repel mosquitoes, but like most repellents, effectiveness varies among users. Electric grids, ultrasonic emitters, electronic repellers and aromatic plants, incense coils, vitamin B1, brewer’s yeast, garlic and wristbands that contain an aromatic repellent are ineffective.

Travel Tips and Mosquito Repellents

Wondering how to protect yourself while traveling in areas with serious mosquito-borne diseases? Malaria is transmitted among humans by female Anopheles mosquitoes and is most prevalent in parts of South America, Africa and South Asia. Mosquitoes need warmth and water to thrive, so take location and seasonality into account when you plan your trip. To avoid mosquito bites while traveling, consider the following:

  • If possible, plan your trip with a mosquito-avoidance strategy in mind. High elevations, desert and coastal areas and other places with colder night temperatures will often have fewer mosquitoes. In dry areas, mosquito activity is much higher during the rainy season, so plan accordingly.
  • If you are traveling to a malaria zone, see your physician prior to travel to determine if an anti-malarial medication is required.
  • Pack a mosquito net. It is essential for travel to some areas of the world when you need to sleep outdoors or in an unscreened room. Hang mosquito nets and close bug screens before dark.
  • Cover up before you get bites, wear loose long sleeved shirts and long pants to reduce skin exposure. Tightly woven cotton will provide better protection than more porous synthetics.
  • As much as possible, apply mosquito repellent to clothing. This is preferable to directly applying a repellent to the skin, but don’t neglect to also use repellent on exposed areas.
  • Don’t spend time near waterlogged ground or other places where mosquitoes breed. Also, avoid outdoor activities at dawn and dusk, when mosquito activity is highest.

Mosquito Repellents

Type of Active Ingredient Representative Chemicals* Hazards Formulation
*For groups of active ingredients of the same type.
Botanicals Eucalyptus oil
Limonene
Nepeta cataria oil (catnip)
Oil of citronella
Oil of lemon eucalyptus
p-Menthane-3,8-diol
Several naturally occurring substances are available as sprays and other formulations. Contact with these common components of foods is not a problem, but inhalation of the spray can be problematic. Oil of lemon eucalyptus is slightly toxic to the central nervous system and has very high ingestion toxicity in children if misused. Lotion, Liquid, Spray, Impregnated materials
DEET DEET poses a low acute toxicity risk to humans. However, there is potential for skin and eye irritation. DEET is a sensitizer, causing allergic reactions in some individuals. Moderately toxic to fish and aquatic invertebrates. Liquid, Spray, Cream, Lotion, Foam, Solid
Ethyl butylacetylaminopropionate (Avon Skin-So-Soft) Low acute toxicity to humans. Eye irritant. Lotion, Cream, Liquid, Spray
Picaridin Low acute toxicity to humans. Eye irritant. Moderately toxic to fish. Cream, Liquid, Spray, Aerosol
Ketones Dihydro-5-pentyl-2(3H)-furanone
Dihydro-5-heptyl-2(3H)-furanone
Methyl nonyl ketone
Poses a low acute toxicity risk to humans and pets. Slightly toxic to freshwater invertebrates. Methyl nonyl ketone is a weak sensitizer, causing mild allergic reactions in some individuals. It is moderately toxic to fish and highly toxic to aquatic invertebrates. Liquid, Spray
Dipropyl isocinchomeronate (MGK Repellent 326) Low acute toxicity to humans, but classified as a probable human carcinogen by the EPA. It is always combined with DEET when found in products intended for human use. It is used to expand the spectrum of repellency for other formulation components. Aerosol, Lotions, Spray, Liquid

Check out the EPA insect repellent search tool for more information on repellents. Beginning in 2015, look for the new EPA graphic on insect repellent product labels to find out how many hours a product will repel mosquitoes when used as directed.

Regulatory Update on Mosquito Control Pesticides

The use of pesticides for mosquito control presents a potential risk to non-target species. On August 15, 2013, the U.S. Fish and Wildlife Service (FWS) proposed to designate critical habitat for the Florida leafwing (Anaea troglodyta floridalis) and Bartram’s scrub-hairstreak (Strymonacis bartrami) butterflies under the Endangered Species Act. Drift from mosquito control pesticide application has been identified as a threat to these species, prompting FWS to recommend the expansion of no-spray zones.

Malathion, naled, phenothrin, permethrin, and pyrethrins are all used for adult mosquito control, primarily through fogging in the early evening. Most of these applications are conducted by vector control districts. Temephos is the only organophosphate with significant larvicidal use and is labeled only for use by public health officials, personnel of mosquito abatement districts or similar agencies or personnel under contract to those agencies. When the registration review for temephos began in 2008, the registrant proposed canceling all uses.  However, due to the need for continued use for mosquito control, this use will not be canceled until December 30, 2015.

References and Additional Resources

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