Mosquito Prevention

With news about West Nile virus in Williamson County and the Zika virus spreading to Texas, it’s important to educate yourself about mosquito-borne diseases.

There is information about West Nile virus on the Center for Disease Control and Prevention and the Texas Department of State Health Services websites. The Williamson County and Cities Health District (WCCHD) has information about the Zika virus.

Other mosquito-borne illnesses include chikungunya and dengue.

The City does not spray for mosquitoes (see below). The best way to limit the mosquito population is to remove their source of life — standing water. We strongly encourage residents to reduce mosquitoes around their home and yard by doing the following:

  • Get rid of old tires, tin cans, bottles, buckets, drums and other containers in your yard or keep them empty of standing water
  • Empty wading pools frequently and store them indoors when not in use
  • Repair leaky pipes and outside faucets
  • Replace your outdoor lights with yellow “bug” lights
  • Change water in bird baths and scrub them twice a week
  • If you have outside pets, empty their watering dishes daily
  • Clean clogged roof gutters and drain flat roofs
  • Treat standing water that can’t be drained with Bacillus thuringiensis israelensis (Bti), available at most home and garden stores

Here are ways to protect yourself:

  • Make sure window and door screens are “bug tight”
  • Whenever possible, remain indoors at dusk and dawn, when mosquitoes are most active
  • When outdoors, wear protective clothing, or use insect repellent with the active ingredient DEET, picaridin or oil of lemon eucalyptus to avoid exposure to mosquitoes. Always read instructions before using insect repellent or other chemicals.

Help spread the word by posting these Fight the Bite flyers from the WCCHD. English | Spanish

City policy on spraying

The City does not spray for mosquitoes. There are many reasons, but the most important are the questions about the effectiveness of the insecticide and the negative impact on the environment. Because of these concerns the City continues to promote the importance of preventing mosquitoes at their source and wearing insect repellent to prevent bites.

Spraying chemicals in Round Rock would not rid the city of mosquitoes. To kill a mosquito, the chemical has to actually make contact with the insect. This may work for a swarm of mosquitoes in a wide-open space with no wind. However, driving a truck down a neighborhood street to spray will do little to kill mosquitoes hiding in grass, bushes, trees and backyards.

Not only is spraying costly and ineffective, there may be serious environmental impacts caused by chemicals. While spraying for mosquitoes may provide a short-term response to the nuisance of mosquito bites, it does nothing to affect the larva present in standing water. The spraying of chemicals also has the potential of contaminating our waterways, killing the beneficial fish and organisms that feed on mosquito larva, adding harmful volatile organic chemicals to the atmosphere — chemicals that cause ozone formation — and providing a potential inhalation or ingestion hazard to residents who are in affected areas shortly after spraying occurs.

Residents themselves can take action against mosquito infestation — see the steps above. The most effective way to reduce mosquitoes in your neighborhood is to remove their source of life — standing water. Thousands of mosquitoes can hatch from a single puddle of water that is stagnant for at least four days.