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National Invasive Species Information Center
U.S. Department of Agriculture
Home / Terrestrial Invasives / Terrestrial Invertebrates / Screwworm

Screwworm

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Screwworm, larva(e)
Screwworm, larva(e) - Photo by Lesley Ingram
Scientific Name: 

Cochliomyia hominivorax (Coquerel) (ITIS; name is valid but unverified)

Common Name: 

New World screwworm, primary screwworm

Native To: 

South America and the Caribbean (CFSPH 2012)

Date of U.S. Introduction: 

Eradicated in the U.S. in 1966 (ARS 1992)

Means of Introduction: 

Could be reintroduced to the U.S. from an infested animal (CFSPH 2012)

Impact: 

Parasite that kills livestock and wildlife, particularly cattle (CFSPH 2012)

Current U.S. Distribution: 
Not currently established

Spotlights

ARS Science Key to Stopping ‘Man-Eating’ Parasite (Jan 4, 2021)

USDA. ARS. Tellus.

Eliminating screwworms from the United States saves farmers and ranchers nearly $900 million in lost livestock each year.

USDA Agencies Work Together to Eradicate an Old Foe: the Screwworm (Jan 9, 2018)

USDA. Blog.

Early in October 2016, the U.S. Department of Agriculture (USDA) was faced once again with New World screwworm, which had been eradicated from the United States more than three decades ago. Infestation of this flesh-eating parasite was confirmed in deer from the National Key Deer Refuge in the Florida Keys.

 

USDA’s Animal and Plant Health Inspection Service (APHIS) immediately began releasing sterile male flies in Florida’s affected areas as part of an aggressive eradication campaign. By March 2017, the screwworm had been successfully eradicated from Florida.

A New World Screwworm Story Map

USDA. Animal and Plant Health Inspection Service.

An interactive story map of the USDA's history of eradicating the infestation and the continuing efforts to keep screwworm out of the US.

Images

Google Images - Screwworm
Google.

Videos

YouTube - Vet Scripts: Screwworms versus Maggots

Google. YouTube; Oklahoma State University. SUNUP TV. 

Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Screwworm.

Partnership
Invasive Species Compendium - Cochliomyia hominivorax
CAB International.
Federal Government
Emergency Management - New World Screwworm

USDA. Animal and Plant Health Inspection Service.

Screwworm Eradication Program Records
USDA. National Agricultural Library.
Sterile Fly Release Programs - Screwworm
USDA. Animal and Plant Health Inspection Service.
State and Local Government
Screwworm Fact Sheet (Nov 2017) (PDF | 313 KB)
California Department of Food and Agriculture. Animal Health Branch.
See also: Cattle Health for more resources
Academic
Animal Disease Information - Screwworm Myiasis

Iowa State University. Center for Food Security and Public Health.

EDIS - Primary Screwworm
University of Florida. Institute of Food and Agricultural Sciences Extension.
Electronic Data Information Source Publication #ENY668

Citations