Solid Waste Management Program

Wetlands Actually Reduce Mosquitoes

A healthy wetland provides habitat for many unique animals - including the natural enemies of mosquitoes.

According to an Indiana Department of Natural Resources fact sheet, Did You Know?...Healthy Wetlands Devour Mosquitoes, mosquito populations are held in check in healthy wetlands by certain birds, frogs, fish, and insects that feed on mosquito adults and larvae. Wetland restoration projects can decrease mosquito populations by providing proper habitat for such predators.

For example, when Essex County, Massachusetts, restored a 1,500 acre wetland, the mosquito population dropped by 90 percent (Audubon Magazine, November-December 1996). Other states, such as New Jersey, have also been controlling mosquitoes the "natural way" by eliminating small stagnant breeding depressions and using water management practices to increase mosquito predators. These "natural methods" reduced the cost of mosquito control, over the traditional method of insecticide application, by more than 97 percent.

When designing wetland restoration projects, considerations should be made up-front for mosquito control. This does not mean that projects should contain only deep or open water. On the contrary, projects with both deep and shallow waters that are somehow connected are generally preferable. Keep in mind to design projects with a variety of water regimes to foster the development of a variety of plants and animals that will naturally include mosquito predators, such as dragonflies, damselflies, water striders, backswimmers, predaceous diving beetles, topminnows, and mosquitofish.

Mosquitoes can be further reduced with the erection of birdhouses that will attract insectivorous birds such as purple martins, tree swallows, and prothonotary warblers. The addition of bat boxes is also a good idea. For example, a single little brown bat can consume 1,200 mosquito-sized insects in just one hour.

For more information, contact Billy Teels, Director, U.S. Department of Agriculture, Natural Resources Conservation Service Wetlands Science Institute, at (301) 497-5938 or contact the Indiana Department of Natural Resources at (317) 232-4080.