When you hear that noticeable, annoying sound, you start fanning or swatting at your ears because you know mosquitoes are out for blood.

All the recent rain and the humidity have created the perfect environment for mosquitoes to breed.

"We've definitely seen an uptick in our service requests through the 311 line," said Joel Lara, the senior environmental health officer for San Antonio Metro Health's Vector Control Services, which keeps an eye on the mosquito population.