Agencies work to put bite on post-Dolly mosquitoes in Rio Grande Valley

Though Hurricane Dolly has come and gone, much of the excess rain she brought is providing a breeding ground for mosquitoes, said a Texas AgriLife Extension Service expert.

“The key issue being dealt with now regarding this first wave of mosquitoes is the annoyance factor – lots of mosquitoes and lots of mosquito bites,” said Dr. Roy Parker, AgriLife Extension entomologist in Corpus Christi. “However, as time passes those species of mosquitoes more likely to transmit disease begin to breed in the standing water that remains.”

Mosquitoes arising from post-Dolly flooding are causing serious discomfort to people in South Texas, especially those who work outside or don’t have electricity or air conditioning, said Department of State Health Services officials in Austin.

Members of that agency have met with Harlingen city officials and Cameron County officials, along with speaking to officials in nearby Hidalgo and Willacy counties.

“Local, state and federal officials are coordinating on where, when and what to spray,” said Roy Burton, a medical entomologist with the department in Austin, who has been working with area officials. “This is a regional approach with county and city health departments. One of the things we’re doing now is surveillance to determine and document mosquito activity.”

Burton said county and city operations already have begun ground spraying.

Area officials indicate plans for aerial spraying in the three counties are being developed, and spraying may begin as early as Friday. The Department of State Health Services is working with other agencies to inform people about the timing and location of aerial spraying.

“Chemical applications are being done by ground by the area entities involved,” he said. “The spraying is being done in the early morning or late evening when the mosquitoes are most active. Local entities are implementing control efforts and our department is providing leadership and technical assistance.”

Burton noted current control efforts are focusing on reducing the number of adult mosquitoes by spraying, killing mosquito larvae and eliminating sources of standing water where more mosquitoes can breed.

“We’re on top of this problem and are working in the interest of public health,” he said.

“The Department of State Health Service is coordinating efforts locally and trying to identify the supplies and treatments for the most effective insect vector control possible,” added Laura Robinson, DVM, the agency’s zoonosis control veterinarian in Harlingen.

“Another important aspect of our efforts is public education,” she added. “We want the public to know what we’re doing and to let them know what they can do to protect themselves and eliminate mosquito breeding conditions.”

Robinson said her agency’s Web site,, provides information on mosquito control, West Nile virus and other pertinent topics.

“People who need to leave their doors and windows open should make sure their screens are repaired and in good condition,” she said. “They can also protect themselves by wearing long pants and long-sleeved shirts, using a repellent with DEET and by judicious use of over-the-counter mosquito control products. Of course, it’s important they read and follow all labeling instructions.”

Parker added that property owners in recently flooded areas can help themselves by locating and emptying anything that may serve as receptacles for standing water.

“Some of the items people may want to investigate for water that’s been standing for a while include flower pots, dog bowls, bird baths, old tires, basins and clogged gutters – anything that can catch and hold water,” he said. “Even standing water in bottles and cans will breed mosquitoes.”

Parker said the mosquitoes breeding in flood water will continue to be nuisance over the next week to two, but less of a threat than those which will appear later.

“After a few weeks, if standing water remains, different types of mosquitoes typically breed in that water, he said. “Disease-transmitting species of Aedes and Culex mosquitoes are stagnant-water breeders, and these are more typically associated with West Nile virus and St. Louis encephalitis. So it’s very important that people eliminate these potential breeding sites.”

Parker said additional information on mosquito control can be found in AgriLife Extension publication E-333, “Mosquito Control Around the Home,” which is available at and on Texas A&M's Agricultural and Environmental Safety Web site at

Other information can be found at

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