screwworm
noun
screw·worm
ˈskrü-ˌwərm 
1
: a blowfly (Cochliomyia hominivorax) of the warmer parts of America whose larva develops in sores or wounds or in the nostrils of mammals including humans with serious or sometimes fatal results
especially
: its larva
2
: any of several flies other than the screwworm and especially their larvae which parasitize the flesh of mammals
Examples of screwworm in a Sentence
Recent Examples on the Web
Europe Central America Australia Asia Answer: The parasite — the larva of the New World screwworm fly — is rife in parts of Central America.
—
Jana Kasperkevic, NBC news, 30 Aug. 2025
The larvae of the New World screwworm flies feed on living tissue, and mainly impact animals and livestock.
—Jenna Prestininzi, Freep.com, 26 Aug. 2025
This person has since recovered, and surveillance programs have not detected any screwworm flies in the surrounding areas.
—Dave Wessner, Forbes.com, 26 Aug. 2025
In the months since, the federal government has faced mounting pressure from agricultural groups worried about the threat of screwworm and its potential impact on the supply chain.
—Rachel Treisman, NPR, 25 Aug. 2025
One case in 2024 was in a Florida man who had traveled to the Dominican Republic and unknowingly had a screwworm fly lay eggs in his nose.
—Jon Brodkin, ArsTechnica, 25 Aug. 2025
New World screwworm, also known as myiasis, is a parasitic infestation of fly larvae that feeds on live flesh, according to the CDC.
—Ashley J. Dimella, FOXNews.com, 25 Aug. 2025
New World screwworm populations have been moving up from South America and nearing the Mexico-Texas border since late 2024, and multiple U.S. and Mexican government health agencies have been working to stop the potential spread of screwworm infestations.
—Moná Thomas, People.com, 11 Aug. 2025
Fighting the parasite with sterile flies Since the first border shutdown to cattle imports, the United States and Mexico have ramped up efforts to surveil, detect and eradicate new cases of New World screwworm.
—Clara Migoya, AZCentral.com, 16 July 2025
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Jana Kasperkevic, NBC news, 30 Aug. 2025
The larvae of the New World screwworm flies feed on living tissue, and mainly impact animals and livestock.
—Jenna Prestininzi, Freep.com, 26 Aug. 2025
This person has since recovered, and surveillance programs have not detected any screwworm flies in the surrounding areas.
—Dave Wessner, Forbes.com, 26 Aug. 2025
In the months since, the federal government has faced mounting pressure from agricultural groups worried about the threat of screwworm and its potential impact on the supply chain.
—Rachel Treisman, NPR, 25 Aug. 2025
One case in 2024 was in a Florida man who had traveled to the Dominican Republic and unknowingly had a screwworm fly lay eggs in his nose.
—Jon Brodkin, ArsTechnica, 25 Aug. 2025
New World screwworm, also known as myiasis, is a parasitic infestation of fly larvae that feeds on live flesh, according to the CDC.
—Ashley J. Dimella, FOXNews.com, 25 Aug. 2025
New World screwworm populations have been moving up from South America and nearing the Mexico-Texas border since late 2024, and multiple U.S. and Mexican government health agencies have been working to stop the potential spread of screwworm infestations.
—Moná Thomas, People.com, 11 Aug. 2025
Fighting the parasite with sterile flies Since the first border shutdown to cattle imports, the United States and Mexico have ramped up efforts to surveil, detect and eradicate new cases of New World screwworm.
—Clara Migoya, AZCentral.com, 16 July 2025
Cite this Entry
“Screwworm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/screwworm. Accessed 9 Sep. 2025.
Copy CitationKids Definition
screwworm
noun
screw·worm
ˈskrü-ˌwərm
: the larva of a blowfly of the warm parts of America that develops in the wounds or sores of mammals and may cause disease or death
also
: the blowfly itself
Medical Definition
screwworm
noun
screw·worm
ˈskrü-ˌwərm
1
: either of two dipteran flies of the genus Cochliomyia:
a
: one (C. hominivorax) of the warmer parts of America whose larva develops in sores or wounds or in the nostrils of mammals including humans with serious or sometimes fatal results
especially
: its larva
2
: a dipteran fly of the genus Chrysomya (C. bezziana) that causes myiasis in Africa and southern Asia
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