Miami-Dade County's mosquito control director says the insect's population is dropping in the Miami neighbourhood health officials have linked to 21 Zika infections.

The Miami Herald reports that at a special county commission meeting Tuesday, Chalmers Vasquez said his department finds just one mosquito a day in each trap in the Wynwood district. He said about two dozen mosquitoes were found daily in the traps two weeks ago.

The county hired contractors to boost its 12-person mosquito control staff to nearly 100 people. Vasquez said his department is responding to thousands of residents' complaints about bug infestations.

Mayor Carlos Gimenez said insecticide is being dropped into 150,000 storm drains. Deputy Mayor Alina Hudak said $300,000 is being spent on ads urging residents to eliminate standing water on their property.