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Screwworm status for U.S. livestock

Plain updates on New World screwworm for ranchers, with links to USDA and your state animal health office.

See USDA case status Opens usda.gov

If you see a wound with maggots

Report it Call your state animal health official or your vet. USDA asks anyone who sees suspicious wounds, maggots, or infestations in animals to report them.
Do not wait Screwworm larvae feed on living flesh. It can kill an animal if not treated.
Keep checking Look at wounds, navels on newborns, and tag or brand sites during warm weather.

New World screwworm

Screwworm flies lay eggs in open wounds. The larvae feed on live flesh. They can kill cattle, horses, sheep, goats, pigs, pets, and wildlife.

What to check

Open wounds of any size
Navels on newborns
Tagging and branding sites
Warm-weather months, when flies are most active

Yearling cattle grazing on open range at the USDA ARS Central Plains Experimental Range in Colorado — Cattle on range at the USDA ARS Central Plains Experimental Range, Nunn, Colorado. Public domain photo by USDA Agricultural Research Service. Source on Wikimedia Commons.

State pages

Verified state sources for places with active U.S. detections or strong official pages. Other states: use the state animal health officials list.

Sources

USDA APHIS current statusOfficial case updates, ports, and trade notes
USDA confirmed detections dashboardPublic case counts for the United States
State animal health officialsUnited States Animal Health Association