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The Texas Animal Health Commission infested zones map.
June 11, 2026
Damaging parasite reaches the Hill Country
By Jessica Nohealapa’ahi
The Bandera Prophet
Three Texas counties have reported cases of the New World screwworm, including Gillespie County outside of Fredericksburg. According to the Texas Animal Health Commission (TAHC), a quarantine in established infested zones is in effect in parts of Kerr, Gillespie, Edwards, Kimble, La Salle, Sutton, Uvalde, Val Verde, Webb and Zavala counties. Executive orders prohibit the removal of any warm blooded animal from those zones without authorization from the TAHC.
The Texas cases reported thus far are livestock, though domestic pets are not immune to the parasites. Eradication of the infestations, which reportedly has begun, involves the release of laboratory-bred sterilized male flies. When they mate with fertile females, which is only once in their lifetimes, the eggs laid are nonviable. According to the USDA, this Sterile Insect Technique poses no risk to wildlife, livestock or people.
The New World screwworm is the larvae of the New World screwworm fly (Cochliomyia hominivorax), which burrow, or “screw” into and feed off of the living tissue of warm-blooded animals, “including livestock, wildlife and humans,” according to the Texas A&M AgriLife Extension Service. The wounds can be serious, and sometimes fatal.
Bandera County native Billy Walker recalled the summer of 1962, when his family’s sheep and goats were injured by a small pack of dogs.
“Although none were killed, the survivors quickly contracted screwworms, and their survival rate was dismal,” Walker said.
“In the 50s and 60s, the screwworm devastated the sheep and goat population,” Pct. 4 Commissioner Jody Rutherford said last year, when commissioners discussed preparing for a possible outbreak. “Measures were taken in the U.S. and Mexico to drive flies further south. They are coming back.”
Ranchers and pet owners are encouraged to monitor and report any suspected cases or signs of the damaging pest, which include foul-smelling wounds with visible maggots, animals biting or licking wounds, lesions, unusual restlessness or lethargy, irritated or depressed behaviors, loss of appetite, head shaking, isolation from other animals or people.
The Texas A&M AgriLife Extension Service in Bandera County will host a pest update program on the screwworm, as well as other pests, at the Mansfield Park Rec Hall on June 23. See more at https://www.banderaprophet.com/260602-bandera-county-pest-program.html.
The Texas cases reported thus far are livestock, though domestic pets are not immune to the parasites. Eradication of the infestations, which reportedly has begun, involves the release of laboratory-bred sterilized male flies. When they mate with fertile females, which is only once in their lifetimes, the eggs laid are nonviable. According to the USDA, this Sterile Insect Technique poses no risk to wildlife, livestock or people.
The New World screwworm is the larvae of the New World screwworm fly (Cochliomyia hominivorax), which burrow, or “screw” into and feed off of the living tissue of warm-blooded animals, “including livestock, wildlife and humans,” according to the Texas A&M AgriLife Extension Service. The wounds can be serious, and sometimes fatal.
Bandera County native Billy Walker recalled the summer of 1962, when his family’s sheep and goats were injured by a small pack of dogs.
“Although none were killed, the survivors quickly contracted screwworms, and their survival rate was dismal,” Walker said.
“In the 50s and 60s, the screwworm devastated the sheep and goat population,” Pct. 4 Commissioner Jody Rutherford said last year, when commissioners discussed preparing for a possible outbreak. “Measures were taken in the U.S. and Mexico to drive flies further south. They are coming back.”
Ranchers and pet owners are encouraged to monitor and report any suspected cases or signs of the damaging pest, which include foul-smelling wounds with visible maggots, animals biting or licking wounds, lesions, unusual restlessness or lethargy, irritated or depressed behaviors, loss of appetite, head shaking, isolation from other animals or people.
The Texas A&M AgriLife Extension Service in Bandera County will host a pest update program on the screwworm, as well as other pests, at the Mansfield Park Rec Hall on June 23. See more at https://www.banderaprophet.com/260602-bandera-county-pest-program.html.