The Richardson Health Department began surveillance of mosquitoes last month to test for West Nile virus.

“As the weather warms, mosquito populations increase. Tracking the presence of West Nile in the mosquito populations allows us to respond with strategic control measures to reduce mosquito populations and reduce the chance the virus makes its way into the human population,” said Director of Health Bill Alsup.

Mosquito surveillance traps are set and collected in 12 areas of the City on a weekly basis each year from late April through October, and mosquitoes are sent to a lab to test for the West Nile virus. If a mosquito sample tests positive for the virus, the management area surrounding the sample’s trap is sprayed. In addition, if a resident is diagnosed with West Nile virus, surveillance traps are placed at or near the person’s home, and spraying is scheduled if a mosquito from these traps tests positive for the virus. If a resident is confirmed to have contracted the Chikungunya or Zika viruses, spraying will be done in a small, localized area due to limited flight range of the type of mosquito that carries these viruses.

The Health Department schedules West Nile virus spraying to begin at 9 p.m. to limit exposure to people who may wish to avoid contact with the pesticide used to control mosquito populations. The goal is to end by 4 a.m., though it may last until 4:30 a.m. depending upon the size of the spray area. Targeted neighborhoods are sprayed twice, on two consecutive nights. The start time, duration and frequency may vary if spraying is done for the Zika or Chikungunya viruses.

To keep the public informed of spraying events, news releases are sent to local media and posted on the City website, and information is sent electronically to homeowners associations and neighborhood associations, as well as to subscribers of the Mosquito Spraying/West Nile e-notification list. Information is also posted on, the Richardson Today Facebook page, NextDoor and the Richardson Today Twitter account.

The best way to protect yourself is by following “The Four D’s”:
Drain standing water,
• Avoid being out at dusk and dawn
Dress in long sleeves and pants
• Apply insect repellent containing DEET or other effective repellents all day every day

Additionally, residents can apply commercially available pesticides according to the label to areas that harbor mosquitoes such as shrubs, groundcover, under raised decks and around storage areas.

Visit for more information, including information about the products used in the City’s spraying and an interactive map of all 12 management areas.