Effectively reducing mosquito populations requires an understanding of the life cycle of the insect. Female mosquitoes must have a blood meal their eggs to mature. She deposits the eggs in small pools of water where they quickly develop into wormlike larvae. Some of the most effective, methods of mosquito control involve killing the larvae or reducing the habitat in which they mature. Old tires, bird baths, flower pots, watering troughs, and poorly maintained gutters are just a few of the human-created water collectors that can provide breeding habitat for mosquitoes. Eliminating these sources is essential to good local mosquito control. In water that cannot be eliminated, biological methods can provide inexpensive long-term control.

           The most common biological control of mosquitoes is fish that eat the larvae before they can mature. Almost any species of fish will eat mosquito larvae if they have access to them. However, the mosquito fish or gambusia (Gambusia spp. ) is the most widely stocked fish species on the planet introduced exclusively to eat mosquito larvae. Gambusia are small fish in the guppy family that 'bear their young alive. They are native to North America but because of stocking' practices can now be found throughout the world in temperate and subtropical areas. Gambusia are excellent biological control for mosquitoes because (1) they can live in the places that mosquitoes develop that often have low dissolved oxygen, (2) they are small (1-3 inches as adults) which makes them easy to handle and transport, (3) they have rapid reproduction rates producing several clutches per year, and (4) they eat mosquito larvae.

           Ditches, canals, and even water treatment ponds can often support gambusia. Only areas that routinely dry completely will not support these insect eating fish. When stocking gambusia in an area that periodically dries consider adding a small refuge pool that is deep enough to retain water in all but the most extensive dry periods. The gambusia can retreat to the pool during dry periods and then re-colonize other areas as the water returns.

          Mosquito fish will live and reproduce well in ornamental ponds. These ponds can be sources of mosquitoes around the home if no fish are stocked in the pond. Koi carp and goldfish win also eat mosquito larvae; however, if the plants in the pond become too thick no fish will provide effective control. Gambusia will eat flake food, pellets, or crumbles along with their diet of insects.

          In larger ponds with established predators like bass and bluegill, add the gambusia directly into the swampy areas and weed beds. With large predators present, it may take more than a single small stocking to establish these little fish. In fact, if there is not adequate refuge, it may not be possible establish gambusia in a bass pond; but, if you can't establish gambusia, it is unlikely that the mosquitoes have a refuge from bluegill and small bass as well. In fact, bluegill and other sunfishes are excellent insectivores that will control the mosquitoes in ponds unless there are excessive weeds in the pond or shallow swampy areas around the edges where they cannot effectively feed. Under those conditions gambusia may be more effective.

Stock the gambusia in the spring after the water begins to warm. There are many sources of gambusia available for stocking. Chances are that gambusia could be found in almost any ditch line with permanent water or many small ponds. Use a dip net or sma11 minnow seine and simply scoop them up. A few dozen fish is all that is needed to get these fish started in a pond. Given their 25-35 day reproduction cycle it may take 2-3 months before the gambusia population will be high enough to control the mosquitoes. The suggested stocking rate for immediate control of mosquitoes is 500­1000 per acre in a pond with no other fish. It is the offspring from these fish that will give the long term control of mosquitoes in the pond.

 

While gambusia can control, mosquito larvae in ditch lines and occasionally in ponds and will not harm the balance in a sport fishing pond, the best controls are to keep weeds under control, reduce swampy areas with proper pond construction, and police the area around the pond to get rid of anything that might hold water and provided a breeding site for mosquitoes.