Boulder County Mosquito Control Program
Mosquito control with a conscience...."You can make a difference!"


The Boulder County Mosquito Control District was established in 1995 by the Board of County Commissioners to protect residents from the health risks, annoyance and discomfort associated with mosquitos. The district encompases 141 square miles of eastern Boulder County. Because the residents that live in the district pay for mosquito control services, Boulder County can only provide service to persons who reside within the Boulder County Mosquito Control District.

Letter to The Editor, Boulder Daily Camera, June 19, 1999.

Environmentally Responsible
The Boulder County Mosquito Control Program (BCMCP) is one of the most environmentally conscious programs in the nation. Mosquito control services in Boulder County are contracted to a private company, Colorado Mosquito Control (CMC). CMC utilizes an Integrated Pest Management (IPM) approach to safely and effectively reduce mosquito populations. All mosquito control materials used in Boulder County have been shown to be non-carcinogenic by the National Cancer Institute and registered for use by the Environmental Protection Agency (EPA).
Integrated Pest Management.....
"The balanced use of cultural, biological, and chemical procedures
that are environmentally compatible and economically feasible to
reduce pest populations to a tolerable level."

Program Highlights
Greater than 94% of the program is biological and physical control of mosquito larvae prior to adult emergence Chemical application for control of adult mosquitos makes up only 6% of the program The program is overseen by a Citizens Advisory Board made up of residents of the Boulder County Mosquito Control District
Mosquitos and Disease Mosquitos are an important part of the ecosystem in Boulder County. Many birds, bats, and other predatory insects feed on mosquitos. However, several species of mosquitos found in Boulder County can transmit disease. The most common diseases that are transmitted by mosquitos found in Boulder County are: Western Equine Encephalitis and St. Louis Equine Encephalitis. These diseases are caused by viruses and have complex life cycles that involve transmission from birds to humans and birds to horses. If these diseases are not caught and treated early, they can be fatal. Flu-like symptoms with swelling of the brain persist with both diseases.
Methods of Control
1. Physical/cultural - involves practices which prevent water from standing for more than four days, such as reparing ditches to prevent seepage, clearing ditches of vegetation to promote rapid flow, and improving drainage channels in irrigated fields.

2. Biological - a naturally occuring bacteria, called Bti, which is toxic only to mosquito and black fly larvae and not to beneficial insects. A native plains fish is used to control mosquito larvae in areas where there is standing water for long periods of time such as wetlands and ponds.

3. Chemical - "Biomist", also known as Permethrin, a man-made version of Pyrethrin which is derived from plants in the Chrysanthemum family, is used as a last resort and only when nuisance threshold values have been exceeded. Nuisance threshold values (mosquito numbers above 100 per trap) are determined by trapping adult mosquitos in annoyance areas. The Biomist is applied at an ultra-low volume so that an extremely small amount of product is applied over a large area (7ounces/acre).

What you can do as a homeowner to control mosquitos

  • Empty or clean out all water-holding containers in your yard (bird baths, tires, cans, rain barrels, wading pools) - 1 small can of water can hold as many as 10,000 mosquito larvae
  • Keep your gutters cleaned
  • Keep ornamental ponds free of weeds, cattails, or other aquatic vegetation
  • Introduce mosquito-eating fish into ornamental ponds. Contact CMC at (303) 466-4515 to obtain fish for your pond(s).

Adult mosquitos are most active at dawn and for about an hour after dusk. Plan outdoor activities during warmer daylight hours or later in the evening to avoid adult biting mosquitos.
  • Keep your lawn mowed as short as possible.
  • Cut back dense vegetation surrounding your yard; this is where mosquitos hide during the day
  • Keep ornamental shrubs and bushes pruned to allow more light and air to flow through them

    Farmers and agricultural landowners
  • Keep irrigation ditches free-flowing and clear of vegetation and debris
  • Repair ditches to reduce seepage
  • Minimize standing water to less than four (4) days in fields
  • Fill tire ruts and hoof prints to avoid puddles
  • Keep horse and cattle troughs clean by changing the water weekly
  • Vaccinate horses for Western Equine Encephalitis
  • Report standing water to CMC at (303) 466-4515.

    Services available upon request if you live in the Boulder County Mosquito Control District
    To obtain services, call CMC at (303) 466-4515
  • answering questions and providing information on mosquito control
  • investigating reports of mosquitoes or standing water
  • excluding your property from spraying - you don't have to be sprayed
  • notifying you before spraying your neighborhood
  • advance 24-hour public notification every Tuesday in the Boulder Daily Camera and the Longmont Times-Call of the
  • areas, dates, and times of spraying for adult mosquitos

    For more mosquito information, check out the Boulder County Mosquito Control District (BCMCD) and the American Mosquito Control Association web page