Garden ponds sometimes get overrun by mosquito larvae.

How to Kill Mosquitoes in a Pond

by Jack Gerard

Although beautiful, garden ponds sometimes provide the perfect breeding ground for mosquitoes. Given the health risks and general discomfort mosquitoes can cause, getting rid of the mosquitoes in your pond should be a priority. While chemical pesticides will kill mosquitoes and their larvae, they sometimes are hazardous to pets and wildlife. Instead, choose natural ways to control the mosquito population and eliminate them from your pond.

Trim the grass and other plants that grow near the pond. Plants that touch the water can promote the growth of algae, giving mosquito larvae shelter while they develop into mosquitoes. Trim or thin aquatic plants, too.

Install a pump system, water feature or other means of circulating the water and increasing its oxygen content. This will reduce algae growth and make it more difficult for mosquitoes to lay eggs in the water.

Introduce fish to your pond that are known for eating mosquito larvae, such as mosquitofish (Gambusia affinis) and top-feeding minnows. The fish will eat larvae before they can develop into mosquitoes.

Place flat, light-colored rocks around the edge of your pond to attract dragonflies if you are unable to add fish. Dragonflies and their larvae are carnivores and will eat the mosquito larvae in the water.

Add a biological pest control disk or brick containing Bacillus thuringiensis to your pond to control or eliminate mosquito larvae. The larvae eat the bacterial mass, which in turn poisons them. Unlike chemical pesticides, Bacillus thuringiensis is not toxic to fish, birds or pets.

Items you will need

  • Pump system or water feature
  • Mosquitofish or other larvae-eating fish
  • Flat stones
  • Bacillus thuringiensis-based pest control agent


  • Some cities and districts provide mosquitofish free to residents.
  • Avoid getting grass clippings or other plant parts in your pond while mowing or trimming. Remove any debris that falls into the water as soon as possible to prevent it from breaking down and encouraging algae growth.


  • Do not place bug zappers near your pond if you are trying to attract dragonflies to control the mosquito population. The bug zappers kill the dragonflies and are ineffective against mosquitoes.
  • Bacillus thuringiensis breaks down in sunlight, so you may need to add several disks over the season. It also requires time to be effective in mosquito control, so you may not see results right away.

About the Author

Born in West Virginia, Jack Gerard now lives in Kentucky. A writer and editor with more than 10 years of experience, he has written both articles and poetry for publication in magazines and online. A former nationally ranked sport fencer, Gerard also spent several years as a fencing coach and trainer.

Photo Credits

  • Ryan McVay/Photodisc/Getty Images