How to Set Up a Mosquito Larva Trap

Photos and article by FMN Jill Spohn

During a talk by Douglas W. Tallamy, an entomologist at the University of Delaware, he suggested controlling mosquitos at the larval stage instead of the adult stage. Spraying adult stage mosquitos requires spraying at such high concentration that it kills all insects, not just mosquitos which results in a loss of beneficial insects as well as nuisance insects.

Beneficial insects such as bees and butterflies and their larva are being eliminated at an alarming rate. Insects are at the base of the food web; without them, birds and other creatures that rely on insects are challenged to find enough food for themselves and their young. When they eat sprayed insects, the insecticide can build up and affect their health.

There is an effective alternative to harmful mosquito spraying – mosquito larva traps

A mosquito larva trap works because adult mosquitos are drawn to a fermenting solution and lay their eggs. The mosquito dunk that is added has a biological bacterial control that ONLY affects mosquitos. Dr. Tallamy noted in an email that this affects only aquatic Dipteran.

I have tried this method at home in Northern Virginia and in Maine and have seen an impressive lack of mosquitos and pleasant times outdoors. I am a believer!

Dr. Tallamy has graciously given me permission to include this section from his book, Nature’s Best Hope, page 210:

Oppose mindless mosquito spraying by your township or HOA. Contrary to what the fogger operator may have told you, the pyrethroid-based insecticides used by mosquito foggers indiscriminately kill all insects, not just the mosquitos. Ironically, targeting adult mosquitos is the worst and by far the most expensive approach to mosquito control, because mosquitos are best controlled in the larval stage. Put a five-gallon bucket of water in a sunny place in your yard and add a handful of hay or straw. After a few days, the resulting brew is irresistible to gravid (egg-filled) female mosquitos. After the mosquitos have laid their eggs, add a commercially available mosquito dunk tablet that contains Bacillus thuringiensis (Bt), a natural larvicide, to your bucket. The eggs will hatch and the larvae will die. This way, you control mosquitos, and only mosquitos, without the use of harmful insecticides.

Learn more about Dr. Tallamy’s work in this video presentation.


It is also essential that you eliminate or reduce the standing water on your property. 

The CDC provides advice on how to control insects at home here and information on the mosquito lifecycle here.

Steps for making a Mosquito Larva Trap

What you need:

  • Bucket
  • Straw or Hay
  • Water – funky water from a rain barrel would also work, says Tallamy
  • Mosquito Dunk or another brand containing Bacillus thuringiensis (Bt)
  • Chicken Wire or similar screening – optional.
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1. Setting Up the Trap

  • Use an empty bucket
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2. Add hay or straw to the bucket. I used 3 or 4 handfuls here – 3 or 4 cups.

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3. Add water to the bucket. I fill the bucket up halfway. My ratio of hay to water is about 1 to 4.

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4. Allow the water and organic matter to ferment for a few days. I usually let it sit for 3 days but if it’s hot, you probably need less time.

5. After 3 days, the mixture has fermented. Add the mosquito dunk.

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Place Mosquito Dunk in the bucket on top of the fermenting solution. Dr. Tallamy may know when a mosquito has laid eggs, but I don’t. I place the Mosquito Dunk in right before I set the trap.

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6. Cover with chicken wire or similar screening that allows adult mosquitos into the solution, but keeps other critters out. Be careful of the sharp points on the chicken wire.

7. Set in place. Dr. Tallamy recommends a sunny spot but I have placed it in dappled shade with good results. The Mosquito Dunk lasts for about a month and I replace the solution after about 3 or 4 weeks.

I try to put the traps close to places where we have had mosquito issues and keep them out of the way of our dogs. They should be out of the reach of children as well.

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