US and Mexico ramp up efforts to stop screwworm spread
The New World Screwworm, a parasitic fly known for infecting livestock, is advancing north through Mexico and is now less than 400 miles from the Texas border. This pest was once eradicated from Texas in the 1970s through a successful USDA program using sterile male flies. These sterile flies, released from planes, disrupted reproduction and pushed the pest south to Panama.
However, in 2023, screwworms slipped through the barrier and began moving north again. Their return poses a serious threat to the state’s multibillion-dollar livestock industry, as the larvae burrow into animals’ wounds, causing infections and sometimes death.
To counter this threat, the USDA has halted cattle imports from Mexico and is investing in a new sterile fly dispersal center at Moore Air Base in Texas. U.S. Senator John Cornyn is also advocating for a new sterile fly production facility, which could cost up to $300 million and take three years to build.
In the meantime, the U.S. and Mexico are spending $21 million to modify a fruit fly facility in southern Mexico to produce sterile screwworm flies. These efforts aim to increase supply and buy time.
Texas Agriculture Commissioner Sid Miller announced that traps containing Swormlure-5 bait will be placed along the Rio Grande. A coalition including the Texas and Southwestern Cattle Raisers Association and Texas Parks and Wildlife has launched screwwormtx.org to keep the public informed.
Ranchers who remember past outbreaks stress the importance of constant animal health monitoring. If screwworms reach Texas, daily vigilance will become vital once again to protect livestock and wildlife industries.
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