The MeatEater Podcast – Ep. 835: Attack Of The Screw Worms

Date: February 16, 2026
Host: Steven Rinella
Main Guest: Dr. Caleb Hubbard, Veterinarian Entomologist (Hubbard Entomology Lab, New Mexico State University)
Notable Panelists: Doug Duren, plus other regular MeatEater crew.

Episode Overview

This episode dives deep into the biology, history, impact, and looming threat posed by the New World screw worm fly—a parasitic insect that feeds on the living tissue of animals. With growing concern about a resurgence of screw worm near the U.S.-Mexico border, host Steven Rinella invites Dr. Caleb Hubbard, a veterinarian and urban entomologist, to explain what outdoorspeople, hunters, ranchers, and the public need to know about detection, management, and large-scale implications of screw worm outbreaks for wildlife, livestock, and pets. Humor and irreverence as always are mixed in, alongside memorable detours into maggot therapies, fly biology, and the public’s role in reporting.

Key Topics and Insights

1. What Is the Screw Worm and Why the Alarm?

• Definition: The New World screw worm is a fly whose larvae feed on living flesh, causing potentially fatal infestations in animals and even humans.

• Outbreak Status: After decades of eradication programs, over 15,000 cases have been reported since 2023 in Mexico, with some just 60 miles from the U.S. border as of November.

  • “It’ll pretty much feed on any vertebrate—cows, wildlife, dogs, even humans or birds. But for the most part, it’s going to be your larger animals, your companion animals, things like that.” – Dr. Hubbard (03:21)

• USDA Stance: Officially, there is “no concern” about reentry to the U.S., but proximity and international spread contradict this.

2. The Uniqueness and Dangers of Screw Worms

• Difference from Other Maggots:

  • “Normal maggots…are after whatever’s going on from the decomposition process, not necessarily digesting rotten protein. But screw worms feed on living tissue.” – Dr. Hubbard (37:49)

• History and Eradication Efforts:

  • First documented in human penal colonies in South America (1858); became a U.S. agricultural crisis by the 1930s.
  • The U.S. led world eradication via ‘sterile insect technique,’ pushing the active population south to Panama.

• Sterile Insect Technique:

  • Releasing irradiated sterile male flies which, after mating with wild females (who mate only once), end reproduction.
    • “Currently, one sterile fly facility in Panama produces about 110 million flies a week.” – Dr. Hubbard (67:34)
  • However, “if it gets into the U.S., we’re going to need 5-600 million sterile flies a week,” more than current capacity.

3. Life Cycle and Clinical Impact

• Life Cycle:
  • Female lays eggs on wounds or soft orifices (mouth, nose, anus, vulva).
  • Eggs hatch in 12–24 hours; maggots burrow into flesh, often undetectable at first.
    • “They’ll go undetected for 2-3 days until the larvae are large enough to be noticed.” – Dr. Hubbard (49:28)
  • Full development in the host: 5–7 days, after which larvae drop to pupate in soil and emerge as adults.
• Lethality:
  • Unchecked, infestations can kill cattle in as little as two weeks.
  • Not just livestock—wildlife and pets equally affected.
  • Outbreak in Key Deer, FL Keys (2016): larvae burrowed into skulls and brains, killing the endangered deer (55:20).

4. Spread, Vulnerability, and Population Impacts

• Transmission:
  • Flies can travel ~10–15 miles; but animal movement is a more significant vector (infected livestock moved between states).
• Wildlife Concerns:
  • Potential for population-level impacts, especially for small/vulnerable populations (Key deer, pronghorns, oryx).
    • “Cattle is focus because we inspect them, but wildlife and feral animal hosts are much harder to monitor.” (99:23)
  • Infected wildlife can form reservoirs, re-seeding outbreaks even if livestock cases are managed.
• Current Risk Zones:
  • Southern states—Texas, New Mexico, Arizona—are at highest risk, with current border animal imports stopped (Santa Teresa port alone accounts for 50% of U.S. cattle imports from Mexico).

5. Limits of Current Solutions—and Infrastructure Crisis

• Reliance on Sterile Technique:
  • The only mass-scale tool. “It's not working—since 2023, new cases move northward despite releases.” (79:25)
• Research Bottleneck:
  • U.S. facilities can’t handle research strains due to containment fears; most chemical/control tools are no longer registered.
  • Only two insecticides under “emergency use.”
• Lag in Preparedness:
  • “It’s a two-to-three-year lag to build a new production facility for sterile flies... and we’re already late.”
• Wildlife Monitoring Gaps:
  • Outreach to hunters, outdoorspeople vital for early detection.
  • Key message: “If you see [infected] maggots or odd wounds in wildlife, report it—hunters will see it first.” (101:05)

6. What Outdoorspeople and Livestock Owners Should Do

• Vigilance:

  • Collect and report samples (kits available in NM; reporting procedures via state ag departments).

• Look For:

  • Festering wounds that expand rapidly, deep cavities with small maggots, distinctive odors.
  • Odd behaviors or deaths in wildlife, especially with wounds or head trauma.

• Resources:

  • USDA APHIS website for case updates.
  • Hubbard Lab: hubbardlab.com and NMSU Urban Entomology on Instagram for ongoing research and education.

7. Broader Biosecurity and Societal Issues

• Border Security:
  • All animal port crossings currently closed to Mexican livestock imports to prevent screw worm entry.
• Public Policy:
  • “It’s not just an animal ag problem—it requires buy-in from public, wildlife agencies, and lawmakers.”
  • Emphasis on non-panic, but proactive awareness.

Notable Quotes & Memorable Moments

The Nature and Horror of Screw Worms

• “One of the things is that I’m trying not to cause panic…but it is a kind of a big problem.” – Dr. Hubbard (02:14)

On Maggot Therapy vs. Screwworms

• “There’s actually a therapy—medical maggot therapy—where maggots are FDA approved to clean out wounds. But these (screwworms) are the ones you don’t want.” – Dr. Hubbard (38:20)

The Calendar Concept

• “We might do one last calendar called ‘Effed Up Wildlife Diseases’—just every month is a picture of a terrible wildlife disease…no one will buy it, but it’ll end the series.” – Steve Rinella (57:09)
• “Or it becomes really, really popular.” – Dr. Hubbard (57:39)

Science and the Public Good

• “My goal here is to make New Mexico an example for everybody else [in preparedness].” – Dr. Hubbard (06:08)
• On population impacts: “There could be a population-level impact where you have vulnerable or isolated wildlife.” – Dr. Hubbard (106:08)
• “If it gets into wildlife, what do you do? Then this runs rampant.” – Dr. Hubbard (84:48)

The Biosecurity Angle

• “All the animal ports of entry are currently closed due to screwworm with Mexico.” – Dr. Hubbard (93:38)
• “Parasites don’t have borders.” – Dr. Hubbard (117:41)

Dark Humor Department

• “The new band name: The New World Screw Worms. Album: ‘Problem of the Americas.’” – Doug Duren (110:09)
• “Screw worm is hardcore. Yeah. Hardcore death metal…The kind you don’t want your kids to listen to.” – Steve Rinella (110:33)
• “You can never trust a reenactor. They inherently are living a lie.” – Steve Rinella (09:10)

Timestamps for Major Segments

• 01:23–06:19 – Introductions, why screw worms are being discussed, Dr. Hubbard’s background.
• 14:13–25:52 – Audience corrections and digressions into wildlife/hunting policy & habitat loss.
• 33:54–38:20 – The history, biology, and control of screw worms; difference from other maggots.
• 48:02–51:53 – Detailed screw worm lifecycle and clinical death process.
• 55:20–62:00 – 2016 Key Deer outbreak: screw worms attacking endangered wildlife, impact and control.
• 66:11–77:13 – How sterile insect technique works, releasing irradiated flies at scale, operational logistics.
• 84:48–94:04 – Bottlenecks in facilities, loss of chemical tools, regulatory hurdles, border closures.
• 97:00–107:40 – Wildlife impacts, population-level risk, the challenge of detection in non-managed species.
• 110:03–122:57 – Final reflections, resources, policy advocacy, Dr. Hubbard’s open request for outdoorspeople to help with surveillance.

Closing Thoughts & Recommendations

• Share Information: The #1 tool is broad awareness; hunters, ranchers, and outdoor users are crucial for early detection.
• Report Suspicions: Maggots or festering wounds in wildlife, livestock, or pets—notify state ag or wildlife agencies.
• Educate Yourself: USDA APHIS and the Hubbard Lab maintain up-to-date resources.
• Advocate: Contact elected officials—urge investment in biosecurity infrastructure and research.
• Support Research: Contributions to local/regional entomology labs directly support monitoring and rapid response.

For in-depth info:

• USDA APHIS Screwworm Page
• Hubbard Entomology Lab, NMSU
• Instagram: NMSU Urban Entomology

This episode delivers a compelling mix of biological science, practical advice, and big-picture policy—all thickly laced with MeatEater’s trademark wit and storytelling. If you’re a landowner, hunter, rancher, or anyone invested in the health of North American wildlife and agriculture, it's essential listening.