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

After a devastating 1972 outbreak in six states — California, Arizona, New Mexico, Texas, Oklahoma and Arkansas — the United States worked with Mexico to largely eradicate the screwworm. —Bay Area News Group, Mercury News, 11 July 2025

So far the screwworms have only been seen in Mexico. —Elizabeth Weise, USA Today, 10 July 2025

But the process of defeating the screwworm may not be quick — or inexpensive. —Kameryn Griesser, CNN Money, 9 July 2025

With the resurgence of the screwworm, several types of animals are banned from import into the U.S. from Mexico, including: live cattle horses bison Screwworms life cycle Where are screwworms located? —Joyce Orlando, Nashville Tennessean, 13 May 2025

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

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