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

It’s called a screwworm because, unlike many fly larvae that feed on dead or decaying flesh, New World screwworm larvae screw into the flesh of warm-blooded animals to feed. — Jen Christensen, CNN Money, 22 June 2026

The screwworm fly is a lousy long-distance traveler. — Ciara McCarthy. Produced With Ai Assistance, Fort Worth Star-Telegram, 22 June 2026

That decrease continued into 2026, as young cattle imports from Mexico collapsed by more than 80% due to the screwworm outbreak. — Andrew Muhammad, Fortune, 21 June 2026

The funding comes a day after the USDA announced $105 million in funding for 40 projects to bolster the nation’s defenses against New World screwworm. — Mateo Rosiles, USA Today, 17 June 2026

Moving from a state with screwworm detection, but located outside the infested and adjacent zones. — Dejanay Booth-Singleton, CBS News, 17 June 2026

New World screwworm is a fly that lays its eggs in open wounds and body openings of warm-blooded animals. — Mary Whitfill Roeloffs, Forbes.com, 16 June 2026

Preventing the spread of screwworm Raff said the screwworms were eradicated in the mid 1900s not just with quarantine, but by the production of male flies that could not reproduce. — Eva Flowe june 12, Charlotte Observer, 12 June 2026

Sterile flies are the primary technique used to eradicate the New World screwworm. — Emily Hallas, The Washington Examiner, 11 June 2026

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