Rain Pulled the Mosquitoes Back Out, and South Texas Cities Are Spraying Into Mid-October

Alton will send a spray truck through town Tuesday evening, weather permitting, the latest South Texas city to run adulticide after a wet stretch reintroduced the one thing October is supposed to be closing down.

The city said the operation depends on conditions, and asked residents to empty standing water from containers, clear clogged gutters and keep outdoor areas free of water that can serve as breeding sites — the same checklist that local governments across the region have been repeating since the first fall rains. The announcement, reported by FOX Rio Grande Valley, also listed the personal precautions: repellent, long sleeves and pants during peak mosquito hours, and attention to any change in the spraying schedule.

Several Valley cities scheduled spraying after the weekend's heavy rain — ValleyCentral published a running list Monday — and Harlingen said last week that it would continue its mosquito spray operations. The rain matters more than the calendar. Culex mosquitoes, the genus that carries West Nile virus, breed in standing water that lingers after a storm, and a warm, muggy pattern that keeps overnight lows near 80 lets those broods mature fast enough to matter in a season that normally tapers off after the first cool front.

The pattern is not confined to the Rio Grande Valley. Kingsville sprayed citywide Thursday through Saturday evenings, and Robstown ran three zones between 3 and 7 a.m. over the same stretch, according to KRIS 6 News — a round of spraying that followed word from Nueces County officials that a mosquito pool in Robstown had tested positive for West Nile virus. Farther up the coast, Crossroads Today reported that Victoria County's spraying program had returned.

State surveillance still shows why the trucks keep rolling. The Department of State Health Services' week-39 arbovirus report, published Oct. 6 and still the most recent weekly snapshot, counted 1,376 West Nile-positive mosquito pools statewide, along with 10 infected birds, 20 veterinary reports and four sentinel chickens. Four deaths have been recorded this year. Harris County alone accounted for 408 of those pools, Dallas 186, and Montgomery, Fort Bend and Tarrant counties between 159 and 162 each. The rounds of spraying in Nueces, Victoria and Hidalgo counties have followed local positives and heavy rain rather than a statewide spike.

Weather is the variable that will settle it. Forecasters expect a cold front to reach deep South Texas by the weekend, and sustained nighttime temperatures in the 50s suppress both mosquito activity and virus development in the insect's gut. Until that arrives, the useful work is local and unglamorous: dump the water in the birdbath and the plant saucers, check that window screens actually seal, and use an EPA-registered repellent with DEET or picaridin when the yard work runs toward dusk.

Cities that already publish schedules — Alton among them — ask residents to watch official channels for last-minute changes, since wind and rain can scrub a night's run. Anyone who sees mosquito activity climbing in an area that has not been treated can say so. Cameron County Public Health, which has been collecting those reports since early October, takes them at (956) 247-3599 or through its online vector reporting tool.