Cattle farmers are hopeful recent investments could control the New World screwworm (NWS) parasite and its current northward migration from Central America.

“The U.S. has defeated NWS before, and we will do it again,” said U.S. Secretary of Agriculture Brooke Rollins. “We do not take lightly the threat NWS poses to our livestock industry, our economy and our food supply chain. We have the proven tools, strong domestic and international partnerships, and the grit needed to win this battle.”

NWS impacts warm-blooded animals like livestock and wildlife. Flies lay larvae near or on animal wounds; larvae then burrow into the flesh and cause extensive, often deadly, damage.

NWS is endemic in Cuba, Haiti, the Dominican Republic, countries in South America and southern Central America. 

Cases have spread north into Mexico, with one reported in Veracruz in early July. That’s less than 400 miles south of the U.S.-Mexico border. To deter screwworm movement, the U.S. halted imports of live cattle, horses and bison through the border May 11 and again July 8.

In June, Rollins introduced a plan to enhance U.S. Department of Agriculture efforts. Tactics include stopping the pest’s movement in Mexico, protecting the U.S. border, maximizing readiness, taking the fight to the screwworm and implementing innovative techniques.

A boon comes through a new sterile fly production facility at Moore Air Base in Edinburg, Texas. It will supplement a production facility in Panama, plus one in Mexico slated to open next year.

Adult screwworm flies are the size of a common housefly. They have orange eyes, a metallic blue or green body, and three dark stripes along their backs.

The sites will produce sterile male flies, which will then be released into large NWS populations. That eventually results in unfertilized eggs — slowing movement of the screwworm. This eradicated NWS from the U.S. in 1966.

Though the threat is still outside the U.S., Alabama Farmers Federation’s Chris Prevatt encouraged farmers to implement health management plans now with assistance from veterinarians and Extension experts.

“This is an external and internal parasite that we are going to have to control,” said Prevatt, the Federation’s director for beef, equine, sheep and goat. “It’s going to require management. It’s going to require getting your livestock up more frequently and checking them. We have to develop really good management protocols so we can deter this parasite.”

Prevatt said while summer fly season is going strong, seasonal hope is in sight. The larvae cannot survive below 46 degrees F, deterring movement in the late fall and winter for most of the southern U.S.