USDA Secretary Brooke Rollins made a stop in Zavala County on Thursday, ground zero in the fight against the New World screwworm.

The county, 100 miles southwest of San Antonio, is where the first screwworm case in decades was discovered.

"This is an all-hands-on-deck approach," Rollins said.

Back in the Rio Grande Valley, many viewers have been asking Channel 5 News if the flies they see are the screwworm fly. Channel 5 News brought those concerns to a doctor at the University of Texas Rio Grande Valley.

Vector-borne disease ecologist Dr. Sarah Maestas studies the ticks and bugs that make animals and people sick.

"This is a pest that is not new," Maestas said.

Dr. Maestas explained that the fly known to carry the screwworm parasite, which feeds on live flesh, looks like a blow fly.

"The New World screwworm is a blow fly, so it has that sort of metallic green or blue coloration of the body. It also has three stripes on the thorax. Typically the middle stripe is shorter than the other two stripes. It has kind of an orange face and red eyes," Maestas said.

Dr. Maestas also said there is another screwworm that feeds on decaying organic material and dead tissue, but that is not the parasite the USDA is fighting against.

If a screwworm infestation appears on an open wound on wildlife, report it to Texas Parks and Wildlife at 512-389-4505. For suspected screwworm cases in livestock and pets, call the Texas Animal Health Commission at 512-719-0700.

Watch the video above for the full story.

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