Spraying for Mosquitoes in the Backyard

 Lots of people are asking about backyard mosquito treatments all of a sudden.  What a change from last year!

The preliminary steps we always mention to prevent mosquitoes are obvious – eliminate standing water, mow tall grass, check the bird bath, etc.  But what about attempting to control the mosquitoes that are already here?  Can I treat my yard and eliminate mosquitoes?

Yes.  Sort of.  Just don't get your hopes too high. 

Treatments you apply in your backyard may provide temporary relief from biting mosquitoes.  For a party or special event, treating mosquitoes makes sense.  As a long term strategy . . . . .  I can think of better ways to spend your money.  Treatment will not last more than a day or two because of migration, so treatment should be applied the day before the event (or the morning of for a late afternoon activity).

Insecticide sprays for mosquitoes should be directed to tall grass, flower beds and shrubs, underside of the deck and other areas where mosquitoes rest.  Homeowner options for treatment include ready-to-use aerosols, a fogger, garden sprayer, or hose-end applicator.  Focus the treatment to flower beds, lawn edges and tall plants.

A fogger is a special machine powered by electricity or propane that produces very fine droplets that hang in the air like fog.  Fogs may float for long periods of time before settling on foliage and other mosquito resting sites.  If you do purchase a fogger, purchase the manufacturer’s fogging concentrate designed to work with that machine and follow instructions carefully.

Aerosol fogs and hose-end applicators are convenient -- no mixing is required.  A compressed-air garden sprayer (thoroughly washed to remove herbicide residues!) can be used to apply garden and lawn concentrates diluted with water.  Higher pressure will produce smaller droplets that will penetrate dense foliage for better control.

Lawn and garden pyrethroid insecticides are a good choice for mosquito treatment.  They are very low toxicity, residual and odorless.  Active ingredients in common lawn, landscape, yard and garden insecticides include cyfluthrin, lambda-cyhalothrin, tetramethrin, phenothrin, and permethrin. Many garden and lawn ready-to-use foggers contain pyrethrin.  Pyrethrin has little to no residual activity and to be effective would have to be used very close to the time of the outdoor event you are trying to protect.

With all lawn and garden insecticides, the minimum re-entry interval is “after the spray has dried.”  Time required to dry depends on humidity and moisture at the time of application and may vary from minutes to hours to overnight, depending on conditions.  Check for reentry statements and other restrictions on the pesticide label and remember to read and follow label directions.

Finally, the alternative to spraying remains use of personal repellents.  Repellents are a great choice for short-term protection against mosquito biting.  Several products are available; pick the ingredient and the concentration that best meets your needs.  Use sparingly to reduce unnecessary or excessive exposure and wash repellent off with soap and water when it’s no longer needed.  For more on repellents, visit the CDC website.  


Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 14, 2013. The information contained within may not be the most current and accurate depending on when it is accessed.