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
Nationwide, screwworm eradication since the 1960s has saved the livestock industry over $1.5 billion per year.
—
Jesus Mesa, MSNBC Newsweek, 23 June 2025
The planned site, slated to be located at Moore Air Base in Texas, will breed millions of sterile male New World screwworm flies.
—Sophia Compton, FOXNews.com, 20 June 2025
An adult New World screwworm fly (left) and a New World screwworm larvae (right).
—CBS News, 18 June 2025
The wider the new front of the screwworm war grows, the more sterile screwworms are needed to stop the parasite’s advance.
—Sarah Zhang, The Atlantic, 27 May 2025
The New World screwworm is the larval form, or maggot, of the New World blowfly, Cochliomyia hominivorax, which resembles a housefly in size and charmlessness.
—Alan Burdick, New York Times, 16 May 2025
Over the last two years, screwworm has spread north throughout Panama and into Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize, and now Mexico, the department said.
—CBS News, 11 May 2025
On May 11, Rollins suspended imports of live cattle, horses and bison across the southern border to combat the spread of screwworm.
—Andrea Hsu, NPR, 30 May 2025
This never-ending battle kept the threat of screwworms far from America.
—Sarah Zhang, The Atlantic, 27 May 2025
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Jesus Mesa, MSNBC Newsweek, 23 June 2025
The planned site, slated to be located at Moore Air Base in Texas, will breed millions of sterile male New World screwworm flies.
—Sophia Compton, FOXNews.com, 20 June 2025
An adult New World screwworm fly (left) and a New World screwworm larvae (right).
—CBS News, 18 June 2025
The wider the new front of the screwworm war grows, the more sterile screwworms are needed to stop the parasite’s advance.
—Sarah Zhang, The Atlantic, 27 May 2025
The New World screwworm is the larval form, or maggot, of the New World blowfly, Cochliomyia hominivorax, which resembles a housefly in size and charmlessness.
—Alan Burdick, New York Times, 16 May 2025
Over the last two years, screwworm has spread north throughout Panama and into Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize, and now Mexico, the department said.
—CBS News, 11 May 2025
On May 11, Rollins suspended imports of live cattle, horses and bison across the southern border to combat the spread of screwworm.
—Andrea Hsu, NPR, 30 May 2025
This never-ending battle kept the threat of screwworms far from America.
—Sarah Zhang, The Atlantic, 27 May 2025
Cite this Entry
“Screwworm.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/screwworm. Accessed 30 Jun. 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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