Episode Details

It’s The Ranch It Up Radio Show! Join Jeff Tigger Erhardt, Rebecca Wanner AKA BEC and their crew as we hear what we need to know and watch out for when it comes to New World Screwworm and what economically it could do if found in the country.  Plus, the latest news, market reports, the ranch channel sales calendar and lots more all wrapped into this brand-new episode of The Ranch It Up Radio Show.  Be sure to subscribe on your favorite podcasting app or on the Ranch It Up Radio Show YouTube Channel.

Season 6, EPISODE 279 What Is New World Screwworm?

The New World screw worm (NWS) is the larval stage of the fly Cochliomyia hominivorax. Unlike most fly maggots that feed on dead tissue, screw worm larvae feed on living tissue — making them especially dangerous to cattle and other livestock.

The adult fly lays eggs in open wounds, including:

• Branding or castration sites
• Dehorning wounds
• Ear tag punctures
• Tick bites
• Navel cords of newborn calves
• Minor cuts or abrasions

Once hatched, larvae burrow into flesh in a screw-like motion — hence the name “screw worm.”

Why New World Screwworm Is A Major Threat To Cattle 1. Rapid Tissue Destruction

Larvae feed aggressively on living tissue, enlarging wounds quickly. Untreated infestations can lead to:

• Severe tissue damage
• Secondary bacterial infections
• Reduced weight gain
• Decreased milk production
• Infertility in breeding stock
• Death in severe cases

2. High Economic Impact

Historically, screw worm outbreaks have cost the livestock industry billions in:

• Treatment costs
• Production losses
• Increased labor
• Export restrictions
• Quarantine expenses

The successful eradication program in the U.S. — led by the USDA Animal and Plant Health Inspection Service — is considered one of the greatest livestock pest control achievements in history.

Signs Of Screwworm Infestation In Cattle

Early detection is critical. Producers should watch for:

• Foul-smelling wounds
• Bloody discharge
• Sudden irritation or head shaking
• Reduced feed intake
• Visible maggots in wounds
• Rapid wound enlargement

Infested cattle often isolate themselves and show signs of distress.

Treatment Protocol For Infected Cattle

If screw worm is suspected:

1. Immediately isolate the animal
2. Notify state animal health authorities
3. Clean and flush the wound
4. Apply approved larvicidal treatments
5. Monitor closely for reinfestation

Reporting is mandatory in many regions because screw worm is a regulated livestock pest.

Prevention Strategies For Cattle Producers 1. Wound Management Best Practices

• Avoid elective procedures during peak fly season
• Use fly repellents and wound protectants
• Monitor surgical sites daily

2. Biosecurity Protocols

• Inspect newly purchased livestock
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