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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)


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

Current U.S. Distribution: 
Not currently established


USDA. ARS. Tellus.

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

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.

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.
See also: APHIS Interactive Maps to explore plant and animal health or wildlife damage management data



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.

Federal Government

USDA. Animal and Plant Health Inspection Service.

USDA. National Agricultural Library.
State and Local Government
California Department of Food and Agriculture. Animal Health Branch.
See also: Cattle Health for more resources

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

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