Screwworm on the Horizon — Vet-Backed Strategies & How Kensington Can Help

The New World screwworm (Cochliomyia hominivorax) may sound like a relic of the past, but recent detections just south of the U.S. border are bringing this dangerous parasite back into focus. Though eradicated decades ago, its potential return underscores the need for horse owners to understand the risks and adopt prevention strategies.

With insights from veterinary experts and the USDA, here’s what you need to know - plus how Kensington can help keep your horse protected.

What Is Screwworm?

• Scientific name: Cochliomyia hominivorax

• The danger: Unlike common maggots, screwworm larvae consume living tissue.

• How it works: Female flies lay eggs in wounds, orifices, or soft tissues → larvae hatch → burrow deeper into healthy flesh.

• Why it matters: This leads to extreme pain, rapid tissue destruction, and often secondary infections.

Veterinary note: Screwworm infestations are not just painful—they can be fatal if not treated quickly. USDA APHIS

A Brief History in the U.S.

• Early 1900s–1960s: Screwworm was widespread in the southern U.S., devastating livestock and equine industries.

• 1966: The USDA declared the U.S. screwworm-free after launching the Sterile Insect Technique program.

• 2016: A flare-up occurred in Florida’s Key deer population—successfully eradicated, but a reminder of the risk.

• 2025: Screwworm was confirmed in northern Mexico, prompting USDA and state agencies to heighten surveillance and prevention efforts. USDA Press Release

What Can Happen If Screwworms Return?

For horses and livestock, consequences can be severe:

• Rapid enlargement of wounds and deep tissue loss

• Secondary infections and systemic illness

• Severe pain, restlessness, anorexia, weight loss

• Costly veterinary treatment (debridement, antibiotics, supportive care)

• Potential death if untreated

Vet insight: Even a “small cut” can become life-threatening when screwworm larvae are involved. Early detection is critical.

Vet-Backed Prevention Strategies

Veterinarians recommend a layered approach:

1. Wound Care

• Clean and disinfect cuts immediately.

• Apply insecticidal wound dressings where appropriate.

2. Daily Surveillance

• Inspect horses for wounds, swelling, or larvae.

• Pay close attention to nostrils, eyes, ears, navel, and legs.

3. Veterinary Support

• Ask your vet about systemic parasite prevention (ivermectin or doramectin, used off-label under guidance).

• Seek immediate vet care for any suspicious wound.

4. Biosecurity Practices

• Reduce sharp edges or hazards in barns and paddocks.

• Control other pests (ticks, biting flies) that can attract screwworm flies.

How Kensington Products Support Protection

While no gear replaces veterinary care, physical barriers reduce fly access, lowering the chance of egg deposition in wounds. Kensington’s fly protection line is a proven, durable choice:

• Fly Masks → Shield sensitive eyes, nose, and ears.

• Fly Sheets → Cover large body areas to prevent fly landings.

• Fly Boots → Protect lower legs, a common site for scrapes and abrasions.

• UV-Blocking Textilene® Mesh → Dual protection: prevents sunburn and resists fly penetration, while staying breathable and comfortable.

Pro tip: Pair Kensington gear with proper wound care and vet-approved insecticides for best results.

Take Action Now

• Stay updated with USDA and state animal health alerts.

• Inspect your horse daily, especially during fly season.

• Use Kensington fly protection to reduce fly contact.

• Report any suspicious infestations immediately to your veterinarian.

Bottom line: Screwworm may not be here yet, but preparedness is key. With vigilant horse care, vet partnership, and protective gear from Kensington, you can help keep your equine partner safe from this devastating parasite.

“Did you know? Screwworm flies can lay up to 400 eggs at a time in a single wound—and the larvae begin feeding within 24 hours.”