The New World screwworm is a flesh-eating parasite the United States spent decades and hundreds of millions of dollars pushing out of the country, and it is back. More than 30 cases have been confirmed as of early July, across Texas and New Mexico, the newest a sheep in Crockett County detected on July 3; the first was a calf in Zavala County in early June [4]. As the fly has spread through cattle country, Washington has done what Washington does. It has found someone to blame.
On the right, the villain is the migrant. Senator Roger Marshall said on Newsmax that 'when millions of people came out of Central America, they brought this screwworm with them' [2]. Agriculture Secretary Brooke Rollins tied the outbreak to what she called the prior administration's failed immigration policies [1].
On the left, the villain is the budget. The Democratic National Committee said the Trump administration is 'directly responsible' for the crisis, having 'decimated' the Agriculture Department's inspection service, with about a quarter of that workforce gone in the 2025 cuts [3]. Representative Ted Lieu blamed the same cuts [1]. Two parties, one fly, opposite culprits.
The people who study the screwworm reject both stories. 'Neither of them are to blame,' the entomologist David Taylor told FactCheck.org [1]. On the migrant claim, researchers say there is no data that migrants carry or spread the fly [1]. On the budget claim, the timeline does the refuting: the screwworm was detected in southern Mexico in late November 2024, two months before the current administration took office and before the staffing cuts, so those cuts could not have caused the outbreak to arrive [1]. Experts allow that the cuts may have weakened the response, which is a fair criticism and a different claim from the one being made.
What actually happened is less useful to either side. The defense that kept the screwworm south of Panama for decades is a program that releases sterile male flies, so wild females mate and produce no offspring. That program degraded. Its lab-raised strain aged and lost its edge against wild males, and the barrier broke down around 2022 [1]. Illegal cattle trafficking, which predates any recent administration, sped the fly's march north but did not start it [1]. From there, Taylor said, reaching the United States was 'inevitable' [1]. A worn-out defense, not a border crossing or a personnel score, is the story.
The reason the blame matters is that it aims the response. Beef is at record prices and the US cattle herd is at its lowest in decades, so an outbreak threatens to keep prices high and to land hardest on ranchers with no margin to spare. The tool that beats the fly is the one that always has: sterile flies, and a lot of them. The Agriculture Department has released about a million across West Texas and is scaling production back up [5]. That is the fight. Blaming a migrant or a budget line does not release a single sterile fly, and the screwworm does not care whose fault anyone decides it is.
