What is screwworm, is it in Cochise County, and how do I protect my dog or livestock?
Written by the Hydra Pest Control team, Arizona-licensed (license #9790)
Last reviewed:
Short answer
New World screwworm is a parasitic fly whose maggots feed on living tissue in wounds and body openings of warm-blooded animals and, rarely, people. USDA confirmed Arizona's first case, a dog in Cochise County, on Oct 28, 2026, and a second case, a horse in Hereford, was reported Nov 2. Check pets and livestock daily for wounds with maggots. If you suspect a case, call your veterinarian and report it to the Arizona Department of Agriculture. Hydra Pest Control does not treat animals or screwworm.
Arizona context
Arizona's first case was a dog in Cochise County. A local veterinarian examined it on the evening of Oct 26 and found a wound on its back heavily infested with maggots, and USDA confirmed the case on Oct 28, 2026. On Nov 2, KTAR reported a second Cochise County case, a horse with no known travel history in Hereford, about 45 miles from the first case. Each confirmed case gets a 20 kilometer (12.4 mile) infested zone, and no animals may leave that zone until movement restrictions are lifted. Check screwworm.gov and the Arizona Game and Fish infested zone map for the latest cases and zones.
What you can do
- Check dogs, horses and livestock every day for draining or growing wounds, maggots or egg masses in wounds, signs of discomfort or irritability, and sores around the ears, nose, genital area and navel (USDA).
- Look closely at small wounds too. USDA says wounds as small as a tick bite can attract the flies.
- If you see maggots deep in a wound, often with a foul smell, call your veterinarian right away.
- Report suspected cases in pets or livestock to the Arizona Department of Agriculture at diseasereporting@azda.gov or 602-542-4293 (8 a.m. to 5 p.m., Monday to Friday).
- For wildlife, call Arizona Game and Fish at 623-236-7201. Note the GPS location, take photos if you can, and do not handle or move the animal.
- Don't buy or apply over the counter antiparasitic products or pesticides on your animals without talking to a veterinarian first (Arizona Game and Fish).
When professional service is warranted
For any animal you think has screwworm, the professional to call is your veterinarian, then the Arizona Department of Agriculture or USDA. Officials control screwworm by releasing sterile male flies, which Arizona Game and Fish says is the only way to eradicate it, along with trapping, surveillance and movement controls. Infested animals should be treated as a veterinarian recommends.
How Hydra handles it
Hydra Pest Control does not treat animals or screwworm, and we are not part of the official response, which is run by USDA and the Arizona Department of Agriculture. Yard spraying and home pest control do not prevent or control screwworm. If you have a question about other pests around your home, talk to an Office Pro at our Sierra Vista branch, (520) 523-8818.
Frequently asked
Is New World screwworm in Sierra Vista?
Arizona's first two cases were both in Cochise County: a dog confirmed by USDA on Oct 28, 2026, and a horse in Hereford reported Nov 2. Officials have not said the dog was in Sierra Vista. Check screwworm.gov for current detections and the Arizona Game and Fish map for current infested zones.
What does screwworm look like on a dog?
Look for a draining or growing wound, maggots or egg masses in the wound, sores around the ears, nose, genitals or navel, and a dog that seems uncomfortable or irritable. Arizona Game and Fish says screwworm maggots sit deep in the tissue and often have a foul smell. Call your veterinarian right away.
Who do I call if I think my dog or horse has screwworm?
Call your veterinarian first. Then report it to the Arizona Department of Agriculture at diseasereporting@azda.gov or 602-542-4293, 8 a.m. to 5 p.m. Monday to Friday. You can also contact USDA through screwworm.gov.
What should I do if I see it on a deer or other wild animal?
Call Arizona Game and Fish right away at 623-236-7201. Note the GPS location, take photos of the wound or larvae if you can, and do not handle or move the animal.
Can people get New World screwworm?
Rarely. Arizona Game and Fish says it can cause painful, infected wounds in people, but with early detection and treatment people do not usually become severely ill. If you have a wound with maggots in it, see a doctor.
Can pest control get rid of screwworm?
No. Officials control screwworm by releasing sterile male flies, along with trapping and movement controls, and infested animals need a veterinarian. Hydra Pest Control does not treat animals or screwworm.
Should I treat my animals with a pesticide?
Not on your own. Arizona Game and Fish says not to buy or apply over the counter antiparasitic products or pesticides without talking to a veterinarian. Follow your veterinarian's advice.
Related on this site
References
- USDA APHIS: USDA Confirms New World Screwworm in Arizona (Oct 28, 2026)
- KTAR: 2nd New World screwworm case in Cochise County confirmed (Nov 2, 2026)
- Arizona Game and Fish Department: New World screwworm case detected in Arizona
- Arizona Game and Fish Department: Prevent the Spread of New World Screwworm
- USDA: screwworm.gov
- Arizona Department of Agriculture
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