For the first time, thousands of live mosquitoes are being released in a Sacramento neighborhood to help prevent disease.

It's a new program we first told you about last month that uses lab-grown insects with the intent of stopping invasive mosquitoes from spreading.

Officials from Sacramento's mosquito control district opened containers with 15,000 live mosquitoes on Tuesday and set them free. The mosquitoes are raised in a Kentucky lab and treated with a bacteria that is harmless to humans but makes the insects unable to breed.

"These male mosquitoes, which don't bite, when they mate with the wild females, the resulting eggs don't hatch," said Luz Maria Robles, with the Sacramento Yolo Mosquito and Vector Control District.

The swarm is being released in Sacramento's south Natomas area, a neighborhood where a large number of invasive mosquitoes have been detected that can cause diseases like Zika and dengue fever.

Marvin Watts saw the crews on his block and thought they were setting traps to kill mosquitoes. He was surprised when we told him they were actually releasing sterile insects.

He's concerned this new program won't work.

"That doesn't make no sense to me. You're killing mosquitoes, but then you want another experiment to release sterilized mosquitoes?" he said.

Mosquito abatement officials say a total of 400,000 mosquitoes will eventually be released between now and November over a 100-acre area of south Natomas.

The program costs just over $32,000. If it's successful, mosquitoes could also be released in other parts of Sacramento and Yolo counties.

"We do hope to see a reduction of invasive mosquitoes and thus protect public health in this area," Robles said.

The mosquito district says they are also seeing an increase in a different species of mosquitoes that can carry West Nile virus, and they will begin ground spraying in parts of Sacramento's Land Park neighborhood and Citrus Heights beginning at 2 a.m. Wednesday.

• Sacramento