State agriculture leaders released a warning to the city and county Monday, announcing that if the process of pesticide spraying to fight the light brown apple moth is delayed, a more lethal pesticide may be needed later, for the action to be successful.

"The risk of greater conventional pesticide is out there," said Steve Lyle, spokesman for the California Department of Food and Agriculture, said in the warning.

The document was issued in response to city and county lawsuit demanding environmental review of the synthetic pheromone before it is sprayed over the entire county.

Last week, state environmental health experts said that illnesses reported by hundreds of residents after the first aerial spraying were not proved to be linked to the pheromone that confuses male moths and keeps them from mating.

But residents still don’t feel safe knowing chemical residue is spread all across the county and Monday afternoon, a group of about 100 mothers and their kids gathered in front of the City Hall in San Francisco to protest against California Department of Food and Agriculture's plan. The women held signs that read: “Keep Your Spray Off My Baby.”

"Nothing gets people more irate than a government institution spraying their kids from a plane," said Jared Blumenfeld, director of the San Francisco Department of the Environment, according to the San Francisco Chronicle. "It's a bad movie. And nobody wants to be in that movie."

Bonnie Kirkland, of the California Alliance to Stop the Spray, San Francisco Chapter, said that other counties also suffered the negative consequences of the spraying and that San Francisco needs to keep its position firmly, so that its citizens’ health is not harmed.

Hundreds of Monterey and Santa Cruz residents reported respiratory problems after the aerial spraying last year.

The protesters claim that spraying may cause not only respiratory problems, but also skin rashes and headaches and even other, more severe, health issues.

Federal and state agriculture officials say that the Australian light brown apple moth invasion is a serious threat to vegetation and agricultural crops and could cause crop damages between $160 million and $640 million each year.