The city of Dallas will spray from trucks through early Wednesday morning. Neighborhoods being targeted are ones where tests have shown a rise in the species of female mosquito most likely to transmit the virus.
The region was the epicenter of the national outbreak last year—the country's worst ever for West Nile virus deaths.
Crystal Woods, Dallas' division manager for mosquito control, says there are no confirmed cases of West Nile in either the city or Dallas County. But she says officials are spraying to stem any outbreak.
Residents are encouraged to stay indoors when the spraying is done.