Nine cases of the flesh-eating fly called the New World screwworm have been detected in the United States as of Friday and what took decades to eradicate only took a few years to return. File Photo by Bill Greenblat/UPI | License Photo

June 12 (UPI) -- Twelve cases of the flesh-eating fly called the New World screwworm have been detected in the United States as of Friday and what took decades to eradicate only took a few years to return.

Since first being detected in Texas earlier this month, the screwworm has spread to southeastern New Mexico, found in a dog. All 12 cases remain active.

The Cochliomyia hominivorax, also known as the New World screwworm, is a parasitic bloatfly that feasts on living tissue. It is the only species of bloatfly that feeds exclusively on living tissue.

"The best thing a rancher can do is put their eyes on their livestock," Stephen Diebel, president of the Texas & Southwestern Cattle Raisers Association, told UPI. "The key to early detection is monitoring livestock and wildlife, knowing the signs and reporting suspicious cases immediately."