Natural Mosquito Control

— Written By Bill Lord and last updated by Margaret Green

2014 is turning out to be a good year for mosquitoes. Warm weather and occasional heavy rain allow for perfect breeding conditions. The recent discovery of mosquito-borne chikungunya virus in North Carolina is one more good reason to control mosquitoes on your property. Mosquito larvae live in stagnant puddles of water. It’s not the larvae that bite us, but the adults that emerge from wet places in our yards like water gardens, flower pots, bird baths, rain gutters, rain barrels, tree holes, pet dishes, decorative ponds or anything else that will hold water for a few days.

Mosquito dunks have been used for over a decade in the United States to kill mosquito larvae before they can turn into biting adults. The dunks are made with Bacillus thuringiensis subspecies israelensis, which is a naturally occurring soil bacteria used as a microbial insecticide to control the spread of vector-borne diseases. According to the EPA, this type of mosquito control does not harm people, pets, wildlife or fish.

The dunks are easy to use, and can be found on-line or at local stores. They can be used in any area that has standing water and are toxic only to mosquitoes. Dunks may be safely used in animal drinking water troughs and bowls that don’t have the water changed frequently. If the water is changed every few days there is no need for the dunks.Even though the dunks are safe, it is not recommended to put them in any container holding human drinking water.

Alternate wetting and drying will not reduce the effectiveness of dunks and the center hole can be used to anchor the dunks in place with a string or stake. The recommended application rates are 1/4 dunk for 1-5 square feet of water surface area and one dunk for 25-100 square feet of water surface area regardless of the water depth. To be sure, always read the label for the exact product you’ve purchased.

Of course the best way to get rid of mosquitoes is to eliminate the aquatic habitats known to produce them. Many times even natural places like tree stumps, or holes in trees can produce mosquitoes. The least preferred method of control is killing the adult mosquito as this requires the use of broad-spectrum insecticides, which can be harmful to fish, birds and other animals.

Mosquitoes do have natural enemies such as bats, birds, and dragonflies, so it is good to encourage these natural enemies by building nest boxes and providing habitat for them. Gambusia, or mosquito fish, are also known to eat mosquito larvae and can be released in ponds and water gardens. Gambusia may be purchased from traveling fish farm trucks. Whatever strategy you choose, prevention is the first line of defense, but if standing water cannot be drained, consider using mosquito dunks as a means of safe, effective, natural control.

Bill Lord

Area Environmental Agent

N.C. Cooperative Extension