06/09/2026
IMPORTANT PSA FOR THOSE IN NEW MEXICO, TEXAS, AND OTHER SOUTHERN USA STATES:
New world screwworm has been detected in Texas (4 cases) and New Mexico (1 case), as of this post. Please stay vigilant and check your animals frequently for signs of screwworm. Report potential screwworm cases to your nearest veterinarian, EVEN IF you do not normally take your animals to the vet. Veterinarians within each state are set up to get maggots to the proper officials for identification, which is ESSENTIAL for rapid screwworm response. As livestock owners, we should all want to contribute to the re-eradication of this pest in North America. Check before you move animals to make sure you are not transporting new world screwworm to a new location.
For some background:
New world screwworm is a type of blowfly that lays its eggs around wounds, eyes, nostrils, and other sensitive areas on warm blooded animals so its larvae can burrow into living flesh. Most blowflies eat necrotic or decaying flesh, but new world screwworm is uniquely dangerous because it continually burrows deeper to access living flesh. Unlike botflies, the new world screwworm females lay tons of eggs on one animal. Before new world screwworm was eradicated from the USA in the 20th century, the fly was occasionally responsible for losses of entire livestock herds. It was eradicated through release of sterile males, which worked because females mate only once in their lives. If a female mates with a sterile male, she will lay infertile eggs and her line won’t continue. New world screwworm was eradicated from North America in the late 20th century, and it was held at the Darien gap until 2022. Since the first breach in 2022, it has slowly moved north. It entered Mexico in late 2024, and this month it was detected in the US (Texas and New Mexico). Federal and state governments are prioritizing identification and eradication of new infestations as they appear. Participation of livestock and pet owners will be key to eradication success.
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