Warm Weather + High Water = Mosquitoes

Recommendations for residents

June 3, 2011

As summer temperatures rise, along with the water levels in creeks and rivers, Garfield County mosquito control and public health officials remind residents that these are prime conditions for potentially large mosquito populations. Several mosquito-borne diseases are endemic to Colorado; and people need to begin using effective prevention measures to protect themselves against disease.

Prevention of mosquito bites
Simple, yet effective, prevention measures can prevent mosquito bites.

  • Avoid mosquitoes by staying indoors at dawn and dusk when bugs are most active.
  • Wear long-sleeved shirts and long pants while outdoors.
  • Apply insect repellent that contains DEET. Follow directions carefully.
  • Install or repair window and door screens to keep mosquitoes out.

The following tips help reduce the number of breeding mosquitoes around the house and lessen the need to use chemical pesticides against annoying adult mosquitoes:

  • Remove standing water in ponds, ditches, clogged rain gutters, flowerpots, plant saucers, puddles, buckets and cans.
  • Check for items that might hold water including wheelbarrows, tires, hubcaps, toys, garden equipment, pool covers, tarps, plastic sheeting, pipes, drains, flat roofs, boats, canoes and trash. Drill drainage holes in tire swings.
  • Completely change water in birdbaths and wading pools weekly. Well-maintained swimming pools and spas are not a risk since pool chemicals kill any larvae.
  • Stock ponds and fountains with fish that eat mosquito larvae.
  • Use mosquito dunks in small ponds. Dunks are natural bacteria that kill mosquito larvae but are harmless to other animals, and are available at home and garden stores.

West Nile virus
Complete information about West Nile virus can be obtained at

Local trapping of adult mosquitoes began June 1. If trapped in significant numbers, Culex species mosquitoes are tested for West Nile Virus. No bird testing is currently being conducted in Garfield County. However, to assist the local West Nile virus surveillance program, citizens can report dead birds to the statewide toll-free help line at 1-877-462-2911.

There is no evidence that a person can get West Nile virus from handling live or dead birds. However, people should always avoid barehanded contact when handling any dead animal. Pick the carcass up with a shovel or gloved hands. Dispose of the bird by double bagging in plastic bags and placing in an outdoor trash receptacle.

Insecticide spraying
Periodically, adult mosquito populations become such that CMC must do an Ultra Low Volume (ULV) insecticide spray application in order to reduce adult mosquito populations to tolerable levels. Anyone who would like to be notified when these mosquito spraying applications are to take place in their area or to ensure insecticides are not sprayed near their property, call CMC toll-free, (877) 276-4306. More information about the Colorado Pesticide Sensitive Registry is available online or call CMC toll-free, (877) 276-4306.

The Garfield County Cooperative Mosquito Control Program also recognizes many people are involved with organic farming and organic home gardening. CMC has products that are certified for use on or near organic crops by the Organic Materials Review Institute (OMRI). Technicians are trained to apply these organic products to areas of larval mosquito production around organic operations. For more information regarding OMRI certified products CMC has available, call (877) 276-4306 or e-mail to info@comosquitocontrol.com.

Symptoms of West Nile virus illness
Even in areas where the virus is circulating, very few mosquitoes are infected, and most are simply a nuisance, but not a health threat. Even if a mosquito is infected, the chances a person will become severely ill from any single mosquito bite are extremely small.

Although it is somewhat rare to catch this illness, and most infected people will have only mild symptoms including fever, headache, body aches, and occasionally skin rashes and swollen lymph nodes, in rare cases, West Nile virus can be fatal. More serious West Nile virus cases can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain’s lining). These infections are characterized by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, muscle weakness or convulsions. Persons with these symptoms need to seek medical attention immediately.

Symptoms generally appear 3 to 14 days after exposure. All residents of areas where West Nile Virus activity has been confirmed could be at risk, but people over age 50 seem to be especially vulnerable to severe forms of the disease.

Mosquito Control