Drought dries out mosquito habitats blocking breeding of bloodsuckers

The devastating drought plaguing South Texas — while taxing the state’s water resources, power grid and lawns — has at least kept the mosquitoes at bay.

Droughts typically destroy mosquito habitats by drying out moist breeding grounds, such as pools of standing water or swampy backyards. With the rare rains this summer, San Antonio has fewer places for these bloodsuckers to swarm and bite people.

Pedro Guzman more than agrees with the scarcity of mosquitoes.

He and his family traveled from their hometown of El Paso for a few days of relaxation in San Antonio — and time away from the West Texas monsoon season.

“I didn’t notice a single bug. It was comfortable, thank goodness,” Guzman said as he fished for talapia in the San Antonio River near Brackenridge Park with his two daughters, ages 4 and 12. , a niece and in-laws.

It was 7 p.m. Thursday. The heat had eased off a bit – from a high of 100 degrees to a slightly more reasonable 95.

He described El Paso at this time of year, with lots of rain and humidity, as a mecca for mosquitoes.

Not that the parasites have completely abandoned San Antonio.

“There are definitely still mosquitoes,” said Texas A&M Agrilife Extension pest control specialist Molly Keck. “But because we are in a drought and there is no standing water in artificial containers or storage ponds and other places where they breed, the population is naturally going to be lower. “

Mosquitoes are attracted to “stinky water,” which is nutrient-rich water containing algae, organic matter, or debris. A paddling pool left unattended in a garden can attract them. The same goes for dirty gutters after a rain or a child’s toy with contours where water can collect. Some species of mosquitoes also breed in stormwater ponds or muddy water that collects in ditches, Keck said.

Mosquitoes lay their eggs in standing water, where their larvae will live until they can buzz around to start breeding. But without the right water, the eggs will not hatch, preventing future adult mosquitoes from continuing the cycle.

The current drought has forced many mosquitoes to look elsewhere for stinky water. Some rivers outside of San Antonio — waterways that have receded and seen substantial reductions in flow — could be more hospitable to mosquitoes than usual, as fast-moving currents give way to stagnant pools. However, these places may not be nutrient rich enough for mosquito eggs to survive.

And if mosquitoes find puddles suitable for breeding on the declining Guadalupe or Medina rivers, they would be too far from San Antonio to bother residents.

At the same time, mosquitoes do not leave. In fact, this year’s record high temperatures – with at least 46 days reaching 100 degrees – are partly offsetting the drought’s damage to mosquitoes.

Warmth is conducive to mosquito breeding, allowing them to complete their life cycle more quickly because their metabolism increases when temperatures rise.

In some species of mosquitoes, the life cycle – in which an insect lays eggs which hatch new mosquitoes which feed, mate and create new eggs – can be as short as a week.

“This area of ​​Texas is pretty hospitable to mosquitoes year-round,” Keck said. “They tend to find a warmer, more protected area to lay down in the colder months, like a little spot on your porch. They will only die if freezing temperatures are maintained and they cannot find a place to hide.

Additionally, higher heat and faster breeding can increase the number of disease-carrying mosquitoes in Texas. There are 85 species of mosquitoes throughout the state, and at least four of them are known to carry and transmit deadly diseases, such as dengue fever, malaria, chikungunya or eastern equine encephalitis – a disease very rare but extremely serious.

Still, Keck said temperature isn’t the most important factor to consider when analyzing mosquitoes. Even if climate change leads to warmer temperatures in the future, it won’t matter if there’s no water. Thus, future droughts will tend to reduce their number.

“If you don’t have a breeding site, that source for them to lay eggs, then you’re not going to see a lot of mosquitoes,” she said.

Staff photographer Sam Owens contributed to this report.

Elena Bruess writes for the Express-News through Report for America, a national service program that places reporters in local newsrooms. ReportforAmerica.org. [email protected]