Brazos County commissioners received an update July 7 on the New World screwworm, an invasive parasitic fly that state and federal officials are working to keep from spreading deeper into Texas.
Texas A&M AgriLife Extension entomologist Sonja Swiger said the pest primarily threatens livestock and wildlife but can also infest pets and, in rare cases, humans.
About the New World screwworm
Unlike common blowflies, Swiger said female New World screwworm flies lay eggs in open wounds on living warm-blooded animals. Once the eggs hatch, the larvae burrow into living tissue, causing severe damage that can become fatal if left untreated.
“That feeding process from larvae is extremely damaging and very invasive and destructive and very fast,” Swiger told commissioners via a public Zoom call.
According to Swiger, more than 31,000 cases have been reported in Mexico. As of July 7, officials were monitoring 28 active cases within 70 miles of the Texas border and 33 total cases in the U.S., including one in New Mexico.
What’s being done
To help contain the spread, federal and state agencies are releasing sterile male flies that prevent reproduction. Swiger said more than 100 million sterile flies are currently produced each week, with releases taking place in Texas and Mexico.
A new production facility in South Texas is expected to open in April 2027.
Swiger said early detection is critical because infestations often go unnoticed for several days, allowing larvae to spread deeper into an animal’s tissue. She encouraged producers and residents to report suspicious infestations rather than attempting to identify the pest themselves.
“A wound on an animal does not mean screwworms but it does increase the chance that maybe they could be susceptible to a screwworm infestation,” she said.
Cases involving wildlife should be reported to local wildlife biologists or game wardens, while suspected infestations in livestock, pets or other domestic animals should be reported to the Texas Animal Health Commission and a veterinarian.
Brazos County Extension Agent Chadd Caperton with Texas A&M AgriLife said local education efforts began in 2025 and have included producer meetings, field days, youth livestock programs and emergency management briefings. Additional outreach is planned later this summer through sheep and goat management programs and other agricultural events.
Stay tuned
On June 17, AgriLife announced it would receive a grant from the U.S. Department of Agriculture for research on the New World screwworm outbreak. Just before then, Texas A&M’s Veterinary Emergency Team deployed June 13 to the Texas Hill Country to help state officials respond to screwworm cases.
Commissioners thanked the AgriLife officials for continuing to educate producers and the public as the situation evolves.
Also on the agenda
- Property purchase: Commissioners approved a $1.825 million contract to purchase a former Department of Public Safety office in Bryan that could become the future home of the Brazos County Elections Administration Office. County Judge Duane Peters said consolidating elections operations into one secure, accessible location would improve efficiency, accommodate new state election requirements and replace the aging Arena Hall voting site.
- Live Oaks Ranch agreement: Commissioners approved a development agreement for Brazos County Municipal Utility District No. 7, which is a planned multiphase residential community in Precinct 1.
Commissioners will meet again July 21 at the Brazos County Admin building.
