Pennsylvania warns backyard flock owners as screwworm quarantine expands

For backyard flock owners, Pennsylvania’s screwworm alert is not just a cattle story. A quarantine now in effect can ripple into bird swaps, exhibitions, rescues and any plan to bring new animals home, because the state is treating New World screwworm as a movement risk that could enter through infected animals even though Pennsylvania’s cold weather would not let it overwinter.

The Pennsylvania Department of Agriculture’s Bureau of Animal Health put the order in place on June 9, 2026, after the parasite was detected in the southern United States. Pennsylvania says it has no confirmed cases, but Agriculture Secretary Russell Redding said the state is moving to protect livestock, companion animals, wildlife and the agricultural economy by limiting animal movements from affected areas. The department is also urging farmers and pet owners to tighten biosecurity and report suspicious wounds with larvae in livestock, pets, wildlife or other warm-blooded animals.

That matters for small-flock keepers because the rules reach beyond big farms. Any domestic animal suspected of infestation, or coming from an affected county or quarantine zone, must be examined by an accredited veterinarian before entering Pennsylvania and declared free of New World screwworm. Animals from quarantined premises cannot enter until a state animal health official clears them. Animals entering from affected areas also need a Certificate of Veterinary Inspection issued within seven days of entry, and the paperwork must include an approved preventive treatment with the product, route of administration and treatment date documented.

The concern grew alongside a fast-moving outbreak in Texas. USDA’s National Veterinary Services Laboratories confirmed a case in a calf in La Salle County on June 9, bringing the U.S. total to six at that point. Texas had already confirmed the first U.S. case of the 2026 outbreak in a calf in Zavala County on June 3, and later detections included a dog in Andrews County. That spread explains why Pennsylvania moved early rather than waiting for a local case.

USDA APHIS says New World screwworm can infest livestock, pets, wildlife, occasionally birds and, in rare cases, people. The parasite was eradicated from the United States in 1966 using sterile insect technique, and a smaller Florida Keys outbreak was eliminated in 2017. Even in a backyard setting, that history is the warning: once animal movement, paperwork and biosecurity slip, a parasite that sounds far away can land right in the coop.