“However, some types of mosquitoes could spread viruses like Zika, dengue, or West Nile.” 
 
 Before we get into the threat of disease, let’s have a look at what large populations of nuisance or floodwater mosquitoes look like. It reported 342 cases of Zika virus during the same period, including one likely spread by a mosquito bite this year.
– Texas has sicced the Air Force on a post-Hurricane Harvey enemy: mosquitoes. As of Tuesday, 1.85 million acres (that's about 1% of the state) had been coated with insecticides via Air Force C-130 cargo planes. The planes had at that point sprayed three eastern counties, with plans to expand their footprint over the next two weeks. Reuters says officials are hoping the effort will tamp down on mosquito-carried diseases like West Nile and Zika, though a rep for the Texas Department of State Health Services says the mosquitoes that tend to materialize after floods aren't usually carriers. What they are: nuisances. That's the word the CDC uses in its Mosquitoes & Hurricanes alert, which agrees that the issue here really isn't disease (though those types of mosquitoes can be a problem a month or two later in areas that didn't flood but saw a big uptick in rainfall). During post-hurricane flooding, "mosquito eggs laid in the soil by floodwater mosquitoes during previous floods hatch. This results in very large populations of floodwater mosquitoes. ... Large numbers of nuisance mosquitoes can affect recovery efforts." How large? Gizmodo has some photos that might make you shudder.