Biological Control

The Warren County Mosquito Commission employs biological control, when appropriate, to reduce larval mosquito populations. Fish, which prey on immature mosquitoes in standing water, are used for mosquito control in suitable locations.

The Commission stocks mosquito eating fish in areas that have documented larval mosquito populations and can support the fish for an extended period of time. Many species of fish are excellent at eating mosquito larvae and pupae, thereby preventing their development into adult mosquitoes and limiting possible disease transmission and/or nuisance problems at that location. Warren County participates in the State Mosquito Commissions’ Biocontrol Program which makes fish available for mosquito control agencies to use throughout the state of New Jersey.

The primary mosquito eating fish species stocked in Warren County include the fathead minnow ( Pimephales promelas ) and the mosquito fish ( Gambusia affinis ). These fish are reared at the state’s Charles O. Hayford Hatchery in Hackettstown, NJ.

Establishing fish populations in areas that are void of other fish but can support fish is the goal of the fish stocking program. Fish can be used in manmade mosquito breeding habitats such as ornamental ponds, unused swimming pools and rain barrels as well as natural habitats including ditches, large woodland pools and contained swamps. Residents can contact the Commission about any area on their property that might be suitable for the use of fish for mosquito control. If appropriate, Commission staff will stock the fish, free of charge.