Grapevine, Colleyville and Southlake all have authorized ground spraying this year for mosquitoes if it becomes necessary.
While the cities have different triggers for spraying, one they all share is whether the Tarrant County Health Department recommends it to prevent the spread of West Nile Virus.
The county this month ramped up trapping and testing for West Nile.
Off-season trapping from April 1 to May 1 did not turn up any positive samples, according to a release from the agency. The nearby city of Flower Mound, just across the Denton County line, had positive samples and started spraying.
