Screwworm Is Back. How Regenerative Producers Are Staying Ahead of It
Screwworm is making headlines again, and cattle producers across the country are asking the same question: what can we do now? For regenerative ranchers, the answer starts where it always has, with the health of the animals.
A Healthy Herd Is a Defended Herd
When asked if regenerative practices and an overall healthy herd make livestock largely immune to screwworm, Will Winter, DVM, Astoria's Chief Grass Evangelist and a holistic livestock health advisor with decades of experience, puts it plainly:
Yes! All livestock must be well mineralized and not exposed to pollution, toxins, and other immune-cripples. This disease is one that hits immune-compromised animals. In bad areas where flies are thick, we recommend our organic and non-toxic fly repellant.
The screwworm fly targets wounded, weakened, or nutritionally depleted animals. A herd in genuine health, properly mineralized, and raised without the immune-suppressing effects of toxins and industrial inputs, is a far less hospitable target. This is what experienced regenerative practitioners observe season after season.
Timing Your Procedures Matters
Even well-nourished cattle are vulnerable if they have open wounds during peak fly activity. Dehorning, castration, and ear tagging all create entry points that screwworm flies exploit. Scheduling these procedures outside of high-risk fly seasons is one of the simplest and most overlooked management decisions a producer can make. If these procedures must be done during fly season, make sure to use an organic, non-toxic fly repellant.
Mineralization: The Foundation
Research from Utah State University found that drought conditions significantly reduce trace mineral availability in forage, driving deficiencies in copper, zinc, manganese, and selenium that directly increase mortality risk. Notably, the study found that testing a herd's actual mineral status and building a targeted protocol from that data outperformed broad, prophylactic multi-mineral injections on both health and cost.
Copper deserves particular attention. Practitioners widely recognize a direct link between copper status and parasite resistance. Adequate copper supports the immune response and the skin's ability to heal minor wounds quickly, closing the door screwworms are looking for.
Apple Cider Vinegar as a Complement
Raw apple cider vinegar has a growing track record among regenerative producers as a low-cost herd health tool. Administered daily, ACV stimulates rumen bacteria, helping cattle extract significantly more energy from forage. Practitioners measure this improved metabolic state through Brix readings in the bloodstream, and link it to stronger overall immunity and radiant health.
There's also evidence that ACV alters an animal's chemistry in ways that reduce fly burden, meaning fewer of the biting insects that create the wounds screwworms target. When combined with minerals in what some producers call "mineral water," a brine of sea salt, bentonite clay, and ACV, bioavailability of those minerals appears to improve. Many operations in the Astoria network have reported rapid resolution of severe fly distress after switching to this combination.
Rotational Grazing Ties It Together
None of these practices exist in isolation. Rotational grazing reduces the concentration of pests in any single area, moves animals away from larval habitat, and gives pastures time to recover in ways that benefit both soil and livestock health. Combined with strong mineralization, strategic procedure timing, and ACV supplementation, it forms the kind of layered defense that keeps screwworm from gaining a foothold.
The producers most likely to weather this outbreak without losses are the ones who have already been doing the work.
Astoria connects buyers directly with regenerative producers who raise their animals this way. If you're looking for pasture-raised livestock from verified operations for your pastures, browse the current listings or reach out to us with your needs.