Mosquito Control In Garden Pools and Ponds

As soon as water accumulates, a potential mosquito breeding place is created. It’s important to be prepared to control it at the time the water is put into the pool to avoid mosquito-borne illnesses such as West Nile virus, malaria, and more.

In many cases new swimming pools are permitted to hold water for several weeks before the final improvements are completed. This period often permits a brood of mosquitoes.


If you feel water is necessary to cure the concrete, drain and allow the pool to become thoroughly dry every four days during this period. Continue reading to learn more about garden pond mosquito control.

Feeding Fish

A good way to control mosquitoes is by making use of their predators. When the pool is permanently filled, add top-feeding fish within three days. This allows ample time for planting and settling of silt and debris before the fish are added. Goldfish, Mosquito fish, Top Minnows or, in areas south of Virginia, the Gambusia, have been used.

These small fish eat mosquito larvae or eggs bred in a breeding ground such as stagnant water like a swimming pool or a frog pond. Don’t feed the fish during the mosquito breeding season. Six or eight fish are sufficient for a pool of about 15 square feet.

The ornamental garden pool is seldom complete without aquatic plants to frame and set off the water-surface. Care should be used in selecting, planting and thinning them as it is around plants that mosquito larvae find protection.

If the vegetation is too dense, fish cannot penetrate to find and eat the larvae. Plants should be thinned out frequently. In selecting plants and fish for the ornamental pool, the aquatic gardener will be glad to advise.

Learn about Mosquito Dunks here.

Natural ponds present problems not found in the masonry-type pool. Usually, the natural pond has a soft mud bottom and, unless the edges are sharp and 12 inches or more in depth, it is difficult to prevent dense marginal growth of plants.

Mosquito control in small ponds depends upon clean margins free from over-hanging grass and sufficient top-feeding fish to keep the water-surface free from mosquito larvae.

Dense growths of aquatics such as cattails, arrowheads or water lilies should be avoided by routine thinning out so that fish can circulate.

As controlling mosquitoes is sometimes difficult when it comes to holding surface-feeding fish over winter particularly when ponds are frozen for long periods, it is suggested that additional stocking be made each spring.

Frogs are also good mosquito killers. They help solve mosquito problems and eliminate other insects that pose a threat to your home environment.

Related: Controlling Mosquitos with Neem Oil?

Natural Larvicide

In some cases, fish are not desired in pools or ponds or are ineffective due to out-of-hand growth of vegetation. In these cases a natural larvicide may be applied to the water-surface at regular intervals or whenever mosquito larvae are seen.

Killing mosquito larvae is an effective way to stop the infestation as male adults would only last up to 10 days while female mosquitoes last up to 50 days. However, a portion of them could die earlier from predators such as spiders, frogs, lizards and other house animals. To kill mosquito larvae in one big swoop, it’s best to find their hiding place in the murky parts of the fish pond or pool.

Mosquito larvae or pupae may be easily found by dipping up water from the surface around the margins or plant stems with a cup. In some cases the larvae are so numerous that they are readily seen on the water surface without the aid of a dipper.

A natural larvicide will not injure plants, fish or waterfowl so great care in application is not required when applied weekly.

In the treatment of ponds that support top-feeding fish it is seldom necessary to treat more than the margins or the dense plant areas.

Mosquito larvae seldom remain in open water when fish are present. Ornamental ponds with no fish should be completely sprayed when mosquito larvae or pupae are present.

Mosquito Dunks at Amazon

The larvicide may also be used as an adult mosquito repellent. By mixing the larvicide in the same dilution and applying a light spray to the grass and a heavy spray into and over marginal shrubs, adult mosquitoes and flies may be killed and discouraged from a yard or picnic area.

The material is best when applied with a garden-type sprayer and its effectiveness lasts from six to 12 hours depending upon the time and the density of the mosquitoes.

Often, under severe conditions, a second application is required at dusk, particularly on the side from which the wind is blowing.

The garden pool or pond can be a source of much pleasure and will add to the scenic value of a property. However, maintenance takes time and effort and the owner assumes a community responsibility in preventing mosquito breeding.

When the pool is no longer desirable, the depression should be filled with earth so that no standing water can accumulate. The neglected ornamental pool is a great source of mosquito annoyance.

image: source

JOIN Our FREE Plant Care Newsletter 

By entering your email address you agree to receive a daily email newsletter from Plant Care Today. We'll respect your privacy and unsubscribe at any time.