Just one fly can lay up to 300 eggs at a time and is drawn "to the odor of a wound or natural opening on a live, warm-blooded animal."

The CDC said screwworms are most common in the tropics and subtropics, but recent cases have appeared in Central America for the first time in years. Mexican authorities told the United States Department of Agriculture in November of a positive detection of New World Screwworm in a cow, according to the Texas Animal Health Commission.

The flesh-eating fly larvae, which were recently detected in Mexico, were declared eradicated from Texas in the 1960s.

Shutterstock / Faisal.k A parasitic screwworm, which was eradicated from the US nearly 60 years ago, is reportedly threatening a return in Texas. According t0 News Nation Now, the New World Screwworm was recently detected in Mexico.