University of Maryland Extension

Controlling Mosquitoes

asian tiger mosquito
Asian tiger mosquito. Photo: Susan Ellis, Bugwood.org

Wearing repellants and eliminating standing water to reduce mosquito breeding sites in your yard are two of the most effective things you can do to protect yourself from mosquito bites. In some communities, spraying for mosquitoes may be done to control large populations and/or mosquito-borne diseases.

Mosquito Biology

  • Mosquitoes are a type of true fly. They go through complete metamorphosis, meaning that they have four life stages: egg, larva, pupa, and adult.  

  • The eggs are laid on or around water and both the larva and pupa stage are aquatic. Mosquitoes can breed in as little as one teaspoon of water.  It can take as little as four days for mosquitoes to complete their life cycle from eggs to adults.

  • Both male and female mosquitoes feed on nectar and pollen as their main food supplies, however female adult mosquitoes will take blood meals in order to get the extra protein needed to lay eggs.  With one blood meal, a female mosquito can lay up to 300 eggs.

Effective Ways to Prevent Mosquitoes from Biting You

  • Mosquitoes cannot bite through clothing so you can reduce the chance of getting bit by wearing long pants and long sleeves.  

  • Clothing treated with the insecticide permethrin will deter mosquitoes (and ticks) from landing and feeding on you.  Make sure to read the directions on how to apply it to your clothing.

  • Protect open skin by wearing insect repellents. When selecting a repellent look for one with DEET, picaridin, Icaridin or oil of lemon eucalyptus. These are registered with the Environmental Protection Agency and the Food and Drug Administration and are effective.

  • Always follow the directions on how to apply a repellent. Put on sunscreen first, then repellent, and never apply repellent under clothing or to pets.

  • Citronella candles, mosquito lamps, and butane-powered repellers have limited effectiveness. The repellent is found in their smoke or vapor so areas where the smoke or vapor does not reach are not protected.  They are best used in small areas over short-term periods, such as camping trips.

Effective Ways to Control Mosquitoes in Your Yard

Large-scale control is hard for mosquitoes due to their ability to fly. Below are some tips to help reduce the number of mosquitoes in your yard.  

  • Mosquito Protection: Bite Them Before They Bite You [video]

  • Mosquitoes breed in standing water, so removing standing water around your home will help reduce the number of new mosquitoes there.  

    • Clean gutters and make sure they drain well.

    • Corrugated drain pipe attached to downspouts hold water and are a prime place for mosquitoes to breed. Use a smooth drain pipe or cover the open end of a corrugated drain pipe with a piece of pantyhose secured with a rubber band.

    • Twice a week, check and remove water that may be standing in trash and recycling cans, flower pot saucers, children’s and pets toys, wading pools, tires, tarps or plastic sheeting.

    • Use goldfish, mosquito fish (Gambusia sp.) or mosquito dunks containing Bacillus thuringiensis israelensis (Bti) in ponds and rain barrels.  

    • Clean and add fresh water every three days to bird baths, pet dishes and pollinator water dishes.

  • Be kind to wildlife. Fish, spiders, beneficial insects, bats, and birds all feed on mosquitoes and provide some natural control.

  • Repair or replace window and door screens that have tears or gaps to prevent insects from coming inside your home.

  • Use fans to keep the air circulating when sitting outside on a porch, deck, or patio.

  • Do NOT use bug “zappers”, mosquito traps, or plants marketed as having mosquito repelling properties. Bug zappers kill beneficial insects and very few mosquitoes since they are on at night when most mosquitoes are not active. Mosquito traps attract more mosquitoes to an area.  There are no plants that have been found scientifically to keep mosquitoes away.

Mosquito Control and the Impacts of Pesticide Use

  • Mosquito chemical control can be in the form of spraying insecticides that target the adults, larva, or both. Spraying insecticides should only be considered after non-chemical methods have been tried and proven inadequate.

  • In Maryland, insecticides registered for use to control adult mosquitoes may include the following active chemical ingredients: naled, piperonyl butoxide, tau-fluvalinate, bifenthrin, and permethrin. (Source: Maryland Department of Agriculture) The latter three of these are in a class of chemicals called pyrethroids. They are broad-spectrum pesticides, meaning they do not target just one type of insect, and may kill or negatively affect bees and other beneficial insects. They are also toxic to fish and other aquatic organisms and should not be applied near a water.  

    Spraying insecticides to control mosquitoes in your yard can be very harmful to pollinators. Read Potential impact of mosquito and nuisance insect sprays on pollinators, from Michigan State University.

  • Area-wide sprays or foggers are only effective temporarily, lasting 1-3 weeks depending on the chemical and the weather conditions. They do not prevent, or protect you from, new adult mosquitoes flying in from surrounding areas after sprays are applied. Repeated spraying of the same chemical can lead to insect resistance to the insecticide.

  • If you are having a private company apply an insecticide to control mosquitoes around your home, ask which chemical they are going to use and for a copy of the chemical label. Before spraying they may ask you to move children’s toys and pet bowls. They might also require you to avoid the area until the chemical has dried.  

  • If you are applying insecticide to control mosquitoes around your home yourself, always follow the directions, wear the correct safely equipment, and follow the re-entry time instructions. Apply first thing in the morning before bees and other insects become active.

Communities Spraying for Mosquitoes

  • There are situations in which local officials will conduct mosquito spraying in communities where there are concerns about the spread of mosquito-borne diseases (e.g., Zika Virus and West Nile Virus).

  • Most of these sprays are done late at night or in the early morning hours in order to reduce the chance of killing non-target insects. However since these sprays are done from the street they might not reach places where mosquitoes are located, such as behind buildings or under porches.

  • The Maryland Department of Agriculture’s Mosquito Control Program maintains a spraying schedule and a list of products used in their mosquito control products. If you would like your home to be excluded from being sprayed, you must fill out a “Request for Exemption Form” and mail it in to MDA. The form can be found on their website here.

References and Additional Resources

Compiled by Christa Carignan, Debra Ricigliano, and Mary Kay Malinoski. Reviewed by Emily Zobel and Jon Traunfeld, University of Maryland Extension 8/2019

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