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

Similarly, imports from Brazil represent only a fraction of what the U.S. imports from Canada and Mexico, which is why the screwworm outbreak in Mexico has been more consequential for U.S. beef prices. —Simon Montlake, Christian Science Monitor, 17 Dec. 2025

The $750 million facility, set to be built in Edinburg, Texas, is slated to produce 300 million sterile flies per week to help combat the New World screwworm parasite, which threatens livestock in North and Central America. —Ashleigh Fields, The Hill, 22 Oct. 2025

The New World screwworm is a parasitic fly that lays eggs in the open wounds of warm-blooded animals. —Lori Ann Larocco, CNBC, 21 Oct. 2025

Also look for screwworm larvae (maggots) and eggs in or around body openings, such as the nose, ears, and genitalia, or the navel of newborn animals. —Beth Mole, ArsTechnica, 24 Sep. 2025

There seems to be a lot of news about screwworm and its risk to farm animals. —Dr. John De Jong, Boston Herald, 24 Aug. 2025

But experts tell the NYT that the U.S. is not ready for the impending screwworm invasion, which is estimated to come within four months. —Cara Lynn Shultz, People.com, 28 July 2025

Meanwhile, the price of medicines used to treat livestock infected with the screwworm have soared in price. —Isabel Mateos, Fortune, 25 July 2025

Word History

First Known Use

1846, in the meaning defined at sense 1

Kids 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

b

: secondary screwworm

2

: a dipteran fly of the genus Chrysomya (C. bezziana) that causes myiasis in Africa and southern Asia