Human and Animal Health Threat
Larvae feed on living tissue causing severe wounds, infection, pain, and potential death if untreated.
New Mexico Awareness
Be Alert, Not Alarmed!
Helping protect livestock, wildlife, pets, and communities with clear information about New World screwworm.
- What is it? New World screwworm is a parasitic fly whose larvae feed on living tissue of warm-blooded mammals. Identification Handout PDF
- Why it matters: Infestations cause severe wounds in animals and humans. Untreated cases can kill an animal in 7-10 days. Although human cases are rare, deaths have been reported.
- Why New Mexico? Regional activity and livestock movement increase the need for vigilance. USDA Story Map
Understand the Threat
Economic Impact
Outbreaks can devastate livestock operations by increasing treatment costs, disrupting production, and affecting rural economies.
Re-introduction Risk
Although eradicated from the U.S., regional outbreaks increase the need for monitoring and preparedness.
Current News
USDA Confirms Presence of New World Screwworm in the United States
Release date:
The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the detection of a New World screwworm (NWS) in a bovine in Zavala County, Texas. NWS is a serious pest that affects livestock, pets, wildlife, and less commonly, people and birds.
Read full article about USDA confirming New World screwworm in the United States
New Mexico officials worry about New World screwworm spreading into state
Release date:
New Mexico state and federal officials this week expressed concern about the encroachment of a parasitic fly into the state, even as federal officials in March unveiled a flurry of efforts to combat the insect's spread.
Read full articleWhat to Watch For
Warning Signs
- Open wounds that worsen or do not heal
- Visible larvae or maggots
- Swelling, discharge, or foul odor
- Animals licking or biting at a wound
- Restlessness, isolation, or unusual behavior
High-Risk Situations
- Recent calving and exposed navels
- Branding, castration, dehorning, or surgery wounds
- Untreated cuts or bites
- Animals moved before wounds are healed
- Warm weather conditions with increased fly activity
Protect Your Animals
Inspect Regularly
Check animals often for wounds, odor, discharge, and changes in behavior.
Manage Wounds
Clean, disinfect, and protect wounds promptly. Isolate animals with open wounds when possible.
View the Animal Drugs for NWS (PDF)Consult a Veterinarian
Work with your veterinarian on diagnosis, treatment, and prevention options.
What To Do
Early reporting helps prevent spread and supports rapid response efforts.
What To DoWhat To Do
If you suspect screwworm infestation, contact your veterinarian or the New Mexico Livestock Board. View the Factsheet: How to Sample for more information on what to do.
Find resources for your situation
In New Mexico, call the New Mexico Livestock Board at (505) 841-6161.
After hours, call the AgroGuard Hotline at 1-800-525-2782 or fill out NMDA's reporting form (Scan QR code for online form).
Sampling kits are available at your local NMSU Cooperative Extension Office (NMSU CES Office) (Scan QR code to find extension office).
Report human infestations immediately to the New Mexico Department of Health at 1-833-SWNURSE (1-833-796-8773) or TEXT NMDOH (66364).
