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 southern Mexico.

To deter screwworm movement, the U.S. halted imports of live cattle, horses and bison through the southern border May 11. 

In June, Rollins introduced a five-pronged plan to enhance U.S. Department of Agriculture eradication efforts. The strategy includes stopping the pest’s movement into Mexico, protecting the U.S. border, maximizing readiness, taking the fight to the screwworm and implementing innovative techniques.

An additional boon will come through a new sterile fly production facility at Moore Air Base in Edinburg, Texas. The $8.5 million facility will supplement the lone sterile fly facility in Panama.

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

The sites will produce sterile male flies, which are then released into large NWS populations. That eventually results in unfertilized eggs — slowing movement of the screwworm.

This technique 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 commodities. “It’s going to require management. It’s going to require getting your livestock up more frequently and checking them. We have to start developing 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 the southern U.S. 

Learn more at aphis.usda.gov/livestock-poultry-disease/cattle/ticks/screwworm.