screwworm

Short definition from Wiktionary

Noun

1. 1
   A larva of a blowfly of species Cochliomyia hominivorax (New World screwworm fly) or Chrysomya bezziana (Old World screwworm fly), of tribe Chrysomyini, parasitic in animals and sometimes humans, distinctive in eating living flesh of mammals, unlike most maggots, which eat only dead flesh.