Mosquito Control

The St. Charles County Mosquito Control Program's major objectives are to:

  • Solicit public participation in reducing the health risk associated with disease-carrying insects through education and action.
  • Provide information and encouragement to eliminate potential breeding sites around home settings.
  • Identify and record potential and historical mosquito breeding sites located in St. Charles County.
  • Monitor breeding sites within St. Charles County and apply treatment to these areas as needed.


The primary goal of the program is to reduce the mosquito population in order to decrease the risk for mosquito-borne disease to the citizens and visitors of our county. The cornerstone of the mosquito control program is the Mosquito Abatement Unit, whose main function is to determine timing and priority of treatment based on larval control and use of citizen complaints.

The program controls immature and adult mosquitoes by seeking out and eliminating breeding sites and by using biological controls or insecticides.

In addition to responding to citizen requests, we also monitor mosquito activity throughout the traditional season.

Please review our report on mosquito control activity during the most recent season and for activity in previous years.

Mosquito Control Requests

St. Charles County residents who are concerned about the mosquito population in their area are encouraged to contact the Division of Environmental Health and Protection using our online form.

What You Can Do

As a resident, you can do more to control mosquitoes around your home than all other methods combined. Proper maintenance of your property is the first step. All trash and refuse that could contain water should be eliminated. The property should be adequately graded and drained to prevent any pools or puddles of water that may last 10 days or longer. In 7 to 14 days, mosquitoes can develop from eggs to adults when conditions are favorable. You can help your local health department by initiating the following practices on your property:

  • Fill in or drain areas where water may stand for more than 1 week.
  • Flatten cans and containers or puncture holes in bottom.
  • Completely seal cesspools and screen all vents.
  • Clean clogged roof gutters and drain flat roofs so no water stays.
  • Cover all standing receptacles, such as rain barrels in rural areas, with netting.
  • Empty and refill outdoor bird baths every few days.
  • Stock garden pools and ponds with small fish or aerate them.
  • Tilt wheelbarrows and machines with containers to prevent holding water.
  • Empty watering cans and wading pools after using.
  • Dispose of old tires or anything that holds water.
After you have done all you can do to reduce the number of mosquitoes on your property, you can protect yourself against the ones that remain by being sure your home is adequately screened, by wearing protective clothing, and by using mosquito repellent whenever outdoors.