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Veterinary Entomology

Screwworm Information

New World screwworm (NWS) is a serious pest of livestock and wildlife.

This invasive pest we previously eradicated from the United States, but has recently been reintroduced (June 2026). Website links below provide information on screwworm, including prevention and treatment for screwworm. Treatment and prevention, as well as reporting requirements, often vary by state - contact animal health officials in your state for state-specific requirements and recommendations.

FEDERAL RESOURCES

USDA-APHIS - Screwworm.gov

US Animal Health Association

Centers for Disease Control

STATE RESOURCES

California Department of Food and Agriculture (CDFA)
- https://www.cdfa.ca.gov/ahfss/Animal_Health/screwworm/
University of California at Riverside
- https://murillolab.ucr.edu/screwworm
Florida Department of Agriculture & Consumer Services
- https://www.fdacs.gov/Agriculture-Industry/Pests-and-Diseases/Animal-Pests-and-Diseases/New-World-Screwworm
Texas Animal Health Commission
- https://www.tahc.texas.gov/emergency/nws.html
Texas A&M Agrilife Extension
- https://agrilifeextension.tamu.edu/new-world-screwworm
New Mexico State University
- https://screwwormnm.org/
University of Tennessee
- https://vectorvbdwatch.tennessee.edu/cochliomyia-hominivorax/

COMMODITY GROUP RESOURCES

AVMA
- https://www.avma.org/resources-tools/one-health/veterinarians-and-public-health/new-world-screwworm
NCBA
- https://www.ncba.org/education-resources/industry-updates-resources/new-world-screwworm-resources
Swine Health Information Center
- https://www.swinehealth.org/wp-content/uploads/2026/01/SHIC-Fact-Sheet-NWS-Considerations-for-Swine-1-2026.pdf
American Sheep Industry Association
- https://www.sheepusa.org/education-resources/animal-health/new-world-screwworrm-resources

House Fly

The house fly (Musca domestica) is a cosmopolitan pest of humans and domestic animals. House flies are generally found in greatest numbers during the hotter summer months. While commonly associated with animal facilities, house flies can also be common in urban areas where garbage, particularly food waste, is not well managed.