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