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

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

The supply curve has already shifted far to the left, and the screwworm threatens to push it even further. — Kevin Williams, CNBC, 10 June 2026

The notorious screwworm has been detected on a handful of Texas farms, and experts say its return will likely keep beef prices elevated for grocery shoppers. — Alexandra Banner, CNN Money, 9 June 2026

As adults, screwworm flies do not bite or feed on flesh. — Emily Mullin, Wired News, 5 June 2026

Diebel, whose family ranch is about 200 miles (322 kilometers) east of the quarantine zone, said ranchers are proactively giving injections that prevent screwworm infestation. — John Hanna, Fortune, 5 June 2026

The New World screwworm is a parasitic fly that feeds on the tissue of warm-blooded animals and people, according to the U.S. Centers for Disease Control and Prevention. — Lillie Davidson, Fort Worth Star-Telegram, 4 June 2026

Largely eradicated in the U.S. since the mid-20th century, the screwworm has recently been detected throughout Mexico, including one instance in September less than 70 miles from the border with the United States. — Joe Hernandez, NPR, 29 May 2026

In the following decades, New World screwworm has steadily returned northward from endemic regions in South America. — Eduardo Cuevas, USA Today, 25 Apr. 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