Denton County Fogging Crews Are Out Through Wednesday Night

If you've spotted a slow-moving truck idling through your neighborhood after dark, that's Denton County Public Health. Fogging crews are working through Wednesday, August 19, running truck-based ultra-low volume spraying between 9 PM and 5 AM — weather permitting — after mosquito traps came back positive for West Nile virus.

This isn't precautionary. Denton County's 2026 interactive mosquito map currently shows two confirmed human cases of West Nile virus in the county. The second case was reported July 30; that person lives in The Colony and was diagnosed with West Nile Neuroinvasive Disease, the more serious form of the illness.

The Argyle corridor has been a recurring hotspot all season. A positive trap south of Argyle triggered fogging in late May. A trap west of Argyle — in the northwestern portions of Harvest — brought another round in late June. Unincorporated areas south of Argyle were fogged again as recently as July 16–22.

The county fogs with ultra-low volume insecticide overnight in unincorporated areas each time a trap tests positive. Incorporated cities and towns like Flower Mound run their own protocols for what triggers ground fogging inside their limits. So if you're inside town limits, the county trucks aren't covering your street — but mosquitoes don't observe city boundaries.

Worth knowing the stakes: most people who contract West Nile never develop symptoms, but about 1% develop the potentially deadly neuroinvasive form, and there are no vaccines or medications to prevent it. Bite prevention is the only lever residents have.

Drain standing water wherever it collects — bird baths, flowerpots, clogged rain gutters. For standing water you can't eliminate, BTI briquettes (sold as mosquito dunks) kill larvae before they mature. Mosquitoes are most active at dusk and dawn, so skipping the evening walk or the backyard sit-out is genuinely the right call right now. When you are outside, long sleeves and an EPA-registered repellent containing DEET, picaridin, or oil of lemon eucalyptus are your best tools.

Detailed maps of the current fog zones are posted at DentonCounty.gov/WNV, along with the interactive trap map. Residents in affected areas are also being notified through emergency alerts and signage. If you think you're in a fogging zone and haven't received anything, the map is the fastest way to check.