West Nile Mosquitoes Confirmed South of Argyle — County Public Health Is Watching

If you spend evenings on your back patio or have a birdbath sitting full of last week's rain, pay attention. A mosquito trap in unincorporated Denton County south of Argyle — a few miles north of Flower Mound's edge — tested positive for West Nile virus this season. No human cases have been reported in Denton County so far, but the virus is in the neighborhood.

One mosquito trap in unincorporated Denton County south of Argyle tested positive for West Nile virus. That was the third positive West Nile virus trap reported in Denton County for the 2026 mosquito season. Since then, five mosquito traps in Denton County have now tested positive, marking the start of the 2026 mosquito season. Local risk levels are currently still low, with no human cases as of this week. Denton County Public Health responded to the Argyle-area find by scheduling ground fogging in the affected area. Truck-based ultra-low volume fogging occurs between the hours of 9 PM and 5 AM.

So the county is doing something. That doesn't mean you're off the hook.

People can contract West Nile virus year round, but cases are mostly prevalent from summer to early fall. August is one of the most active months, according to CDC data. We are heading directly into the window when this gets worse — not past it. The virus shows up in mosquitoes before it shows up in people, which is exactly why these trap results matter.

The numbers are worth knowing. Roughly 80% of people infected with West Nile never experience symptoms. About 20% will develop West Nile fever — fever, headache, nausea, muscle and joint aches, and fatigue. Less than 1% will contract West Nile neuroinvasive disease, a serious neurological illness that can cause tremors, convulsions, neck stiffness, disorientation, paralysis, and even death. There are no vaccines to prevent it or medications to treat it. Older adults and people with weakened immune systems face higher odds of landing in that worst category.

Texas sees this every year. According to DSHS, Texas has reported 976 total West Nile cases over the last five years, including 106 deaths linked to the virus. During that span, 2024 had the most recorded deaths at 57, while 2025 fatalities were the fewest at nine. The year-to-year swings are real. Nobody knows yet what 2026 looks like.

What you can actually do. Start in your yard. Rainfall can boost breeding grounds for mosquitoes, which only need as little as a bottle cap-size pool of stagnant water to reproduce. Health officials recommend dumping standing water in places like clogged rain gutters, rot holes in trees, boat covers, outdoor pet bowls, old tires, trash bins, buckets, flower pots and saucers, and birdbaths. Check those spots regularly. New mosquitoes can breed and hatch quickly after water accumulates. For ponds or water features you can't drain, health officials recommend mosquito dunks — a solid larvicide also called Bti briquettes — that kill mosquito larvae before they grow into biting adults.

When you're outside: mosquitoes bite day and night but are most active at dusk and dawn — health officials recommend avoiding outdoor activities at those times. While outdoors, dress in long sleeves and long pants and use insect repellent with DEET, picaridin, or oil of lemon eucalyptus.

The Argyle trap is not in Flower Mound. But the mosquito doing the biting doesn't know that. Detailed maps of fogging areas and the latest mosquito surveillance data are at DentonCounty.gov/WNV. Check it. Drain your gutters. Wear repellent at dusk. Small moves, right now, while the season is ramping up.