Natural mosquito control

It's possible to help reduce mosquito populations around a home through the use of natural or biological means. Predatory fish, plant repellents, bacteria and even other mosquitoes can all take their toll on the mosquitoes that breed and feed in a given area.

In addition to traditional ways to get rid of mosquitoes, try these natural methods:

Mosquitofish

The Gambusia is a small, freshwater minnow-like fish native to the Southeastern U.S. They are surface feeders and will eat mosquito eggs and larvae by the hundreds every day. A dozen gambusia are good for about 48 surface feet of water.

The fish are hardy, capable of surviving in stagnant water, grow only to about two inches in length and breed to the size of their container to prevent overcrowding.

Most local mosquito control programs use the fish and often provide them for free to homeowners with mosquito problems.

Because mosquitofish also feed on the eggs and young of other insects and fish, they should be used only in water that does not connect to lakes, streams or rivers. Improper use of the fish is suspected in the extinction of same native species of amphibians.

They may need to be replaced each year if used in an area that dries out, such as a seasonal marsh or swamp.

Dragonflies

These insects may look like scary biters, but they are only dangerous to mosquitoes. Dragonfly larvae, “nymphs,” feed on mosquito larvae, and adult dragonflies feed on adult mosquitoes.

The key to attracting dragonflies is to provide an environment that is comfortable and safe for them. A small pond, shallow at one end and deep at the other, with vegetation that grows out of the water and plenty of flat rocks surrounding it should do just fine.

The nymphs will eat mosquito larvae in the water, and the adults will sun themselves on the rocks, waiting for the adults to leave the water.

Some towns in Maine have been buying and releasing dragonfly nymphs in local waters for decades and insist the insects help keep local mosquito populations under control.

Citrosa, lemon thyme and rosemary

These and several other plants reportedly contain oils that are repel mosquitoes. The citrosa is even marketed as the “mosquito plant” for its supposed success in keeping the insects away.

However, the problem with using any plants to repel mosquitoes is that the oil is not naturally released into the air from an undisturbed plant. The leaves must be crushed before the oil is released, and even then it does not spread far.

That does not necessarily mean these plants do not have a place in natural mosquito control, though.

Many of them have a pleasant smell and can be planted in high-traffic areas in the yard, especially around patios, decks and rear doors, so that people passing by disturb the leaves. People also can pluck the leaves and rub them on their skin while outdoors.

Bacillus thuringiensis israelensis

This naturally occurring bacteria is used as a larvacide in ponds and other areas where mosquitoes are breeding. The larvae die when they feed on it in the water.

Bti is commercially produced by companies that grow it in fish meal or soy flour and sell it in pellets. The pellets are sold at home and garden stores, usually by the brand Mosquito Dunks. The pellets can just be dropped into water, where they will float and slowly release Bti.

Once the larvae eat the bacteria, it develops into several toxic substances in their stomachs, quickly killing them.

Bti is not harmful to animals, birds or even most other insects. It is effective against larvae only and has not effect on adult mosquitoes.