New World screwworm larva, like the one pictured, will hatch and feed on the flesh of living animals, typically cattle. “This is the first human case of travel-associated New World screwworm myiasis (parasitic infestation of fly larvae) from an outbreak-affected country identified in the United States,” Nixon said. An adult New World screwworm fly. After feeding, the larvae fall into the ground, burrow into the soil and emerge as adult screwworm flies, continuing the cycle. Through this technique, the U.S. managed to eradicate New World screwworm in 1966.