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

Because the screwworm has moved so far northward in recent months, U.S. officials are increasingly concerned about the risk to border states like Texas. —Brandi D. Addison, Austin American Statesman, 2 July 2025

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

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