McALLEN, Texas (Border Report) — The deadly parasitic New World screwworm has been spotted less than 400 miles from the Southwest border and is threatening Texas cattle, lawmakers say.

U.S. Sen. John Cornyn, R-Texas, says the screwworm flies could devastate the state’s cattle industry if it crosses onto U.S. soil.

“A case of the New World screwworm was reported less than 400 miles south of the U.S.-Mexico border,” Cornyn told colleagues Monday on the Senate floor. “It may soon come across the border and lead to an outbreak in our state.”

The screwworm was first reported in Mexico in November and has steadily made its way north since then.

The most northern recent reported case was in Ixhuatlan de Madero, in the state of Veracruz, Mexico, which is about 370 miles south of McAllen, Texas, according to the U.S. Department of Agriculture.