Austin's mosquito days decline
Add Axios as your preferred source to
see more of our stories on Google.
We're not the only ones lying low in triple-digit temperatures. Austin's increasingly hot summers have led to a decline in the number of days hospitable for mosquitoes.
Driving the news: A recent report from nonprofit science research organization Climate Central found that while many cities have seen an increased number of "mosquito days," some locations — particularly in the South — are actually getting too warm for mosquitoes, Axios' Alex Fitzpatrick reports.
- Mosquitoes don't thrive in temperatures above 95° F.
- Heat index values could reach 107° today, and the city broke its all-time heat index record of 118° last week, amid the ongoing heat wave.
Yes, but: That doesn't necessarily mean there are fewer mosquitoes in the area overall, according to Sonja Swiger, a professor and entomologist at Texas A&M University.
- Texas has 88 species of mosquitoes, which adjust to conditions by changing their habitat or seasonality. Mosquitoes in Central Texas are typically most active from May through November.
- Early data from A&M and Harris County show that the bugs seem to be spending their time underground in the sewer systems to escape the heat, Swiger tells Axios.
Why it matters: Mosquitoes are more than just a nuisance — they're a public health threat, carrying diseases such as malaria, West Nile, Zika and more.
- Austin health officials said a mosquito pool in East Austin returned a positive test for West Nile virus. No positive cases of the virus have been detected in people yet.
- Plus, a person in Cameron County and four people in Florida contracted malaria over a period from late May to late June through local transmission, the first time the disease has been spread by mosquitoes locally in the U.S. in 20 years, per the CDC.
The big picture: Climate Central defines a "mosquito day" as one with an average relative humidity of 42% or higher, plus daily temperatures of 50° to 95°.
- 71% of the 242 locations Climate Central analyzed saw an increase in mosquito days between 1979 and 2022, of about 16 days on average.
- But the number of mosquito days in Austin, for example, is notably trending downward from 208 annual days in 1979 to 129 annual days in 2022.
Zoom in: Austin Public Health typically sees fewer mosquitoes in traps during extreme heat, according to Aaron Urbanek, according to Aaron Urbanek, an environmental health officer with the city.
- But there are many variables that can play a role in the increase or decrease in population, such as stagnant water or a yard with tall bamboo and trees.
What they're saying: "We are seeing extreme heat earlier, and if we maintain these temperatures for longer, it will make mosquitoes less likely to take blood meals and reproduce, which will reduce their numbers," Urbanek tells Axios.
The bottom line: Expect mosquitoes to hide out in cooling areas and be less active during the hottest time of the day, Urbanek added.
Dig deeper: Where mosquito days increased