How to Kill Mosquitoes in Water Fountains

Female mosquitoes lay their eggs in fountains, as well as ponds and any other places around your yard that hold or collect water. Keep the fountain pump on to circulate water, which makes your fountain less attractive to mosquitoes. A natural, pet-safe mosquito-killing tablet decimates existing larvae before they hatch into mosquitoes.

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Getting Rid of Existing Mosquito Larvae

Adult mosquitoes don't live in the water, but are naturally drawn to it and lay their eggs in it. Controlling the larvae as they hatch prevents more mosquitoes from terrorizing your yard. To kill the larvae, add mosquito larvicide tablets to the fountain. These larvicides are made from bacteria, Bacillus thuringiensis israelensis, also known as BTi. BTi, found naturally in soil, targets mosquito larvae specifically and is not harmful to mammals, birds or fish.

Using BTi Mosquito Larvicide

Most BTi tablets are made for small ponds and the usual dose is one disc for each 100 square feet of water surface, which covers most fountains. Read the larvicide packaging as products vary.

Place one mosquito larvicide disc in the fountain, or in each level of the fountain, if more than one level contains water at all times. For fountains with significantly less than 100 square feet of water surface, break the disc first and use only one-half a disc or less for each area. The discs float for a while and eventually sink, mixing in with the water. Mosquito larvae eat the BTi and it kills them before the become adult, biting mosquitoes.


  • Add fresh larvicide to the fountain every 30 days, or whenever you replace the old water with fresh water.

Natural Ways to Nix Mosquitoes

Besides the larvicide treatment, the best way to prevent mosquitoes is to make the fountain area less attractive to them.

  • Keep the fountain pump on at all times -- mosquitoes prefer to lay eggs upon still or stagnant water.
  • If you don't use the fountain, empty it and cover it to prevent water from collecting when it rains. 
  • Trim back any tree branches and overgrown plants that may serve as hiding places for adult mosquitoes.  
  • Empty plant pot trays, pet dishes and other objects that collect water. 
  • Replace water in birdbaths or kiddie pools every several days to prevent stagnant water that attracts mosquitoes.


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