Ouch! Mosquito facts & what you can do to prevent mosquitoes

May 30, 2014
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Mosquitoes are the worst! They ruin outdoor events, crash your picnics and can even invade your house to bite you while you sleep. Follow our advice and don’t let mosquitoes take over your summer.  


Why Do Mosquitoes Seem to Be Everywhere?

Mosquitoes breed in stagnant, standing water – as little as a teaspoon or bottle cap of water standing for more than a week is enough for eggs to develop into adult mosquitoes. People tend to overlook the small amounts of standing water, such as those that collect underneath potted plants and in tire swings.

Plus you can be bit during the day or at night!

The Asian tiger mosquito is non-native and bites during the day, while the native Culex species is most active at night.  They seem to be everywhere, because without proper diligence, they are!



Tips for Reducing the Number of Mosquitoes

The most important advice we can give:  Prevent Standing Water!  

  • Clean out roof gutters and down-spout screens
  • Flush birdbaths and saucers under potted plants at least once a week


Image of a faucet dripping


  • Turn over children’s wading pools, buckets, wheelbarrows, canoes and garbage can lids.
  • Drain water trapped in folds and arrange tarps so water runs off
  • Fix dripping outdoor water faucets
  • Dispose of trash such as plastic bags, bottles, open drink cans, or food wrappers.  Even a bottle cap can hold enough water for a mosquito to breed.


Image of trash left on the ground


  • Check recycle bins if they are left out in the rain.  Dump water out.
  • Throw away used tires.  If you have a tire swing, drill holes in the bottom of the tire so water will drain out.
  • Drain water that collects on swimming pool covers.
  • Add an aerator to your birdbath or ornamental pond.  Mosquitoes do not breed in moving water.  They prefer standing water.


Should I Use a Larvacide?

DEP recommends trying all the methods above to reduce mosquitoes before trying a larvacide.

Larvacides kill mosquito larvae (not pupae or adults).  They are a preferred treatment over the use of adulticides because of their effectiveness in controlling mosquitoes and in minimizing impacts to the environment and to non-target organisms. They are also not harmful to animals such as squirrels, raccoons and dogs if they are ingested.

There are two recommended types of larvacide:

  • Bacillus thuringensis var. israelensis (B.t.i.) is a bacterial larvacide that is most readily available from local stores.  They are also called Mosquito Dunks®.  However, this larvacide kills other aquatic insects in addition to mosquito larvae, so it should NOT be used in water that flows into natural water bodies. B.t.i. can be used in small containers of water around residential properties, private rain gardens, rain barrels and other areas that do not flow into streams, lakes or rivers.
  • VectoLex® (Bacillus sphaericus) is a naturally occurring bacterium found in soil and aquatic environments. It produces a stomach poison (endotoxin) which is specifically toxic to mosquito larvae after it is ingested.  Because it only targets mosquito larva, VectoLex® is safe to use in natural water bodies (not drinking water reservoirs) or in water that flows to natural water bodies such as stormwater facilities and storm drains.  VectoLex® can only be purchased and applied by a licensed applicator.


Image of a rain barrel

I Think the Mosquitoes in My Yard are Coming From the Nearby Stormwater Facility.  What Should I Do?

A stormwater management practice (pond, sand filter, rain garden, etc.) that is properly maintained and functioning should not support mosquito breeding.

  • Most stormwater practices drain water out within three days and do not provide enough time for mosquitoes to reach adulthood.
  • Wet ponds have large amounts of standing water, however, they are also designed to be natural aquatic habitats.  Wet ponds include natural predators to mosquitoes that eat the larvae.  Frogs, fish, salamanders, dragonflies and aquatic insects all prey on mosquitoes and prevent them from reaching adulthood.

If you think a stormwater management practice is not functioning properly, contact the Department of Environmental Protection.


Graphic of a family staying inside because of mosquitoes.

I Want to Learn More!

Visit the American Mosquito Control Association or the Maryland Department of Agriculture Mosquito Control Section for more information.

Share the information you learned with your friends and neighbors.  Download and print out our brochure that includes the information listed here and more.  Download the mosquito brochure. (PDF, 847KB)


Slider Photo by James Jordan, Creative Commons License, Flickr

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