by John Jefferson

I well remember the screwworm siege of the ‘50s and ‘60s. The ghastly pictures of deer and cattle with half their faces eaten off — or an eye missing — stay with you. Our field staff at TPWD filed unforgettable images.

The insidious screwworm flies lay eggs in any body entrance – open wounds like barb wire scrapes, nasal and eye openings, buck deer fighting wounds, and other orifices. It happens to any warm bloodied animal – including pets.

When screwworm eggs hatch, the maggots burrow into tissue by screwing their bodies into the flesh to feed — hence, their name. According to a release by the Texas Standard news service, a Texas entomologist named Edward Knipling was one of the researchers discovering a temporary cure by sterilizing male screwworm flies. Female flies can only breed once, so, if they fell for a male shooting blanks, motherhood didn’t happen. (I don’t understand all that and don’t have room for it anyway; just know it was successful!)

That saved untold livestock, wildlife and a monitory fortune! The disease wasn’t eliminated but was pushed south into Panama and Guatemala. Reports say it’s been discovered in a cow in Chiapas, Mexico in 2024. That’s a long way away, but bad news and fly-borne diseases travel quickly.

An outbreak among Florida’s Key Deer in 2016 eliminated 14% of the rare deer according to information from the Texas Wildlife Association. Rapid response with sterile flies ended the pestilence in just six months.

Screwworm are surviving in Cuba, Haiti, Dominican Republic, and South America. But this time, science knows how to eliminate them. The plant that raises the sterile male screwworm flies is located in Chiapas, near where the host cow was detected. It is operated by the joint Mexico-U.S. Commission for the Eradication of Screwworms.

The affected Chiapas cow was confirmed last November. Sterile male flies were continually dropped by the U.S. Agriculture Department. Difficulties with Mexico ended that, however. The U.S Ag Secretary, Rollins, then temporarily closed the border to Mexican cattle importation.

A livestock professor and economist at Texas A&M, David Anderson, said, “It would be pretty devastating if we were to get it (screwworms) back.”

Many agreed that another sterile fly plant is necessary — among them are the former Biden screwworm director, a Texas rancher and cattle health committee chair for the Texas and Southwestern Cattle Raisers Association (Wayne Cockrell), and U.S. Representative Tony Gonzales, whose district includes 800 miles of the border.

When screwworm legislation was considered in the fifties, some legislators joked about the flies’ name. But there was nothing funny about their destruction. Texas livestock industry, hay and grain farmers, hunting operators, and many small towns in hunting areas suffered damages estimated in the billions of dollars during the last screwworm invasion.

Farmers are always a drought away from disaster. Deer hunting is a much larger industry today. So, damage figures could be much higher if a recurrence strikes. Screwworms MUST be held at bay!

If you agree, contacting your state legislators would help.

JJ