screwworm

American  

[skroo-wurm] / ˈskruˌwɜrm /

noun

1. the larva of any of certain flies of the genus Callitroga, which sometimes infests wounds and the nose and navel of domestic animals and humans.

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screwworm British  

/ ˈskruːˌwɜːm /

noun

1. the larva of a dipterous fly, Callitroga macellaria, that develops beneath the skin of living mammals often causing illness or death

2. the fly producing this larva: family Calliphoridae

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Etymology

Origin of screwworm

An Americanism dating back to 1875–80; screw + worm

Example Sentences

The spread of New World screwworm in Mexico and the slow pace of herd rebuilding add uncertainty to future beef supply and prices.

From Barron's • Mar. 5, 2026

"But we do hope that this project will help people to be more vigilant in recognizing and preventing screwworm infestations in animals should they return to California."

From Science Daily • Dec. 17, 2025

That said, much more is driving beef inflation than tariffs and the screwworm.

From Los Angeles Times • Nov. 19, 2025

But the Department of Agriculture this spring suspended Mexican cattle imports after the screwworm parasite was detected in herds south of the border.

From The Wall Street Journal • Nov. 11, 2025

As Phil explained to Patches while they watered their horses, the screwworm is the larva of a blowfly bred in sores on living animals.

From When A Man's A Man by Wright, Harold Bell