An infestation of flesh-eating screwworms is spreading throughout the Florida Keys, which can harm wildlife, livestock, pets and humans.

The screwworm is the larvae of the screw fly and is the only insect known to eat the living flesh of warm blooded animals, the U.S. Department of Agriculture said.

The infestation is the first instance of screwworms being found in the U.S. in more than 30 years, and was first found in Big Pine and No Name keys. It's now spread to Big Torch, Middle Torch, Little Torch, Cudjoe and Ramrod keys.

The outbreak has already had a serious impact on critically endangered Key Deer, the FDA said. Screwworms have caused deaths of nearly 10 percent of the endangered 1,000-member herd of Key deer found only in the Florida Keys.

Pet owners are encouraged to check their animals for any wounds for signs of the parasitic larvae.

As of Oct. 19, 883 pets had been inspected by Federal and state officials at a checkpoint in Key Largo, and none were found to have screwworm.

Florida Commissioner of Agriculture Adam H. Putnam declared an agricultural state of emergency on Oct.3.