The 5 Most Disturbing Things You Need to Know About the Screwworm Infestation Panic
- It’s a literal internal flesh-eater: The screwworm isn’t a typical maggot. It is the larva of the New World screwworm fly, and unlike other fly larvae that eat dead tissue, these parasites burrow into living, healthy flesh. They create deep, oozing wounds that smell like rot while the animal is still alive, causing severe pain, secondary infections, and often death if untreated.
- A single female can decimate an entire herd: One pregnant screwworm fly can lay up to 400 eggs on a simple scratch or tick bite on a cow, sheep, or dog. As the larvae hatch, they tunnel into the wound, attracting other flies. An infested animal left untreated can collapse from infection and tissue damage, making a single fly a ticking time bomb for livestock operations.
- It’s mysteriously returning to the US after a 50-year absence: The USDA declared the screwworm eradicated from the United States in 1966 using a sterile insect technique (releasing millions of sterile males). However, in late 2024, a major outbreak was confirmed in the Florida Keys, and cases have since popped up in Texas and California. The exact source of the re-infestation is still under investigation, but climate change and accidental shipment from endemic regions are the prime suspects.
- The treatment is as horrifying as the infestation: To save an infested animal, vets must physically remove every single live maggot from the wound—one by one—using forceps. This is a slow, agonizing process for the animal. After removal, the wound is treated with potent insecticides and packed with bandages to prevent re-infestation. For wildlife like deer and endangered Key deer, the process is near-impossible without sedation.
- The “sterile male” weapon is back