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

The Food and Drug Administration is working to authorize the emergency use of some drugs and pesticides to treat or prevent New World screwworm infections. —Clara Migoya, AZCentral.com, 23 Sep. 2025

Brazilian beef faces a 76% tariff, and the USDA has blocked livestock from Mexico to the U.S. due to concerns over the screwworm parasite. —Brittney Melton, NPR, 22 Sep. 2025

The bacteria does not technically eat tissue like screwworms do. —N'dea Yancey-Bragg, USA Today, 28 Aug. 2025

By Jason Gale, Bloomberg The US has confirmed a case of the flesh-eating parasite New World screwworm in a person in Maryland, who had traveled from Guatemala and has received treatment for the infection, Reuters reported. —Bloomberg, Mercury News, 25 Aug. 2025

Earlier this month, the FDA issued an Emergency Use Authorization (EUA) for animal drugs to treat or prevent infestations caused by screwworm. —Youri Benadjaoud, ABC News, 25 Aug. 2025

Veterinarians may also use drugs that are approved for other uses to treat screwworm infestations. —Madhusree Mukerjee, Scientific American, 25 Aug. 2025

Decades ago, screwworms were endemic throughout Central America and the southern US. —ArsTechnica, 8 Aug. 2025

President Donald Trump’s administration on May 11 announced a halt on imports of live cattle, horses and bison over the southern border because of an outbreak of the screwworm fly, whose flesh-eating larvae can kill cattle. —Afp, Fortune, 10 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