Early reporting could protect livestock and wildlife
Contributed Article/Courtesy AZGFD
PHOENIX — The Arizona Game and Fish Department (AZGFD) is asking the public to be on the lookout for the New World screwworm, a destructive pest that poses a threat to wildlife, livestock, pets, and rarely, people, after a recent detection in New Mexico.
On September 17, 2026, the United States Department of Agriculture (USDA), working with the New Mexico Livestock Board and New Mexico Department of Agriculture, announced that a horse was identified with a New World screwworm (NWS) infested wound in Grant County, New Mexico.
This is the first affected equine identified in New Mexico, and the responsible authorities are working on the epidemiologic investigation and area surveillance. This case is approximately 50 miles from the Arizona border. Details on the New Mexico infested zone, adjacent surveillance zone, and other response information may be found on www.screwwormnm.org.
New World screwworm has not been detected within Arizona’s boundaries, but recent detections in Texas, New Mexico, and northern Mexico pose a risk of spreading into the state.
Adult New World screwworms are parasitic flies that lay eggs in open wounds or mucous membranes such as the nostrils, eyes, navels, or mouths of live warm-blooded animals; these include birds and mammals. The eggs hatch into a type of larva (maggot) that only feeds on living tissue.
As you hunt or recreate outdoors, please check harvested game and observe live animals you encounter for:
- Larvae (maggots) on live or very recently deceased animals. Unlike other maggots, New World screwworms feed on living tissue and will vacate an animal once it has died and the tissue begins to cool.
- Maggots live deep in tissue with a foul odor. Common sites are wounds or body openings like the nose, eyes, or genitalia.
In the event that you suspect screwworm:
- Take a GPS location.
- If it is wildlife, contact the Arizona Game and Fish Department immediately at 623-236-7201. Do not handle or transport the animal.
- Take pictures of the wound, larvae, or affected animal, if it is safe to do so.
- If it is a domestic animal (livestock, pets), contact the Arizona Department of Agriculture at diseasereporting@azda.gov. If in doubt, reach out to your veterinarian for assistance.
Resources to aid in the identification of NWS can be found here.
The Arizona Department of Agriculture (AZDA) is leading an extensive and proactive effort to protect and prepare Arizona for the possible spread of New World screwworm. AZGFD is working closely with the AZDA and USDA in support of this effort.
Targeted releases of sterile NWS flies are being expedited to eliminate any reproducing populations in the area associated with the detection. When combined with enhanced surveillance, movement restrictions, prompt treatment of wounds, and education and outreach efforts, the sterile insect technique is a proven and effective tool for controlling and eradicating this pest.
Your reports are critical for early detection and rapid response. Vigilance and quick action could protect wildlife and livestock across the state.
More information on NWS can be found at screwworm.gov and azgfd.gov/screwworm.
