HOUSTON – Recent cold snaps across Southeast Texas may have brought freezing temperatures, but they did not eliminate mosquitoes, according to Harris County Public Health.
“We have year-round mosquitoes here in Harris County,” said Dr. Courtney Stanley, director of the county’s Mosquito and Vector Control Division, during a Zoom interview Friday. “There is no end to mosquito season.”
Stanley said mosquito surveillance traps have already collected about 27,500 female mosquitoes in January, a number that may surprise residents who assume winter weather brings mosquito activity to a halt.
While colder temperatures can reduce mosquito activity temporarily, Stanley said freezes in Harris County are typically not cold or long-lasting enough to kill mosquitoes.
“What you will see is mosquitoes finding warm habitats, inside homes, sewer systems, drains and yards,” she said. “If it’s warm and wet, mosquitoes are going to hunker down and wait it out.”
Mosquitoes can enter a dormant state known as diapause during cold weather, slowing their activity until temperatures rise again. However, Stanley said it would likely take a week or more of sustained subfreezing temperatures to significantly impact mosquito populations, conditions that are rare in the Houston area.
Certain species, including Culex mosquitoes that can spread West Nile virus, often shelter in sewer systems and around homes, allowing them to survive cold snaps.
Health officials say mosquito-borne diseases remain a concern year-round. Harris County Public Health recently reported positive mosquito samples for West Nile virus, including detections in January, a first in the county’s 20-year digital record.
In general, mosquito-borne illnesses are more common between May and October, but Stanley said cases are increasingly appearing later in the year due to changes in weather patterns and habitat.
Residents are urged to protect themselves using the department’s “tip, toss and take action” approach:
- Tip out standing water.
- Toss items that can collect water, such as tires, buckets or bottle caps.
- Take action by using EPA-approved insect repellent, wearing long sleeves and reporting mosquito problems.
Harris County residents can request inspections or report mosquito issues by calling 713-440-4800. Officials also encourage residents to report dead birds, which can be an early indicator of mosquito-borne viruses.
“Mosquitoes are here year-round,” Stanley said. “The best thing people can do is stay aware and reduce standing water whenever possible.”