Secondary-screwworm
Guides
Cochliomyia macellaria
secondary screwworm, secondary screwworm fly
Cochliomyia macellaria, the secondary screwworm, is a blow fly in the family Calliphoridae distributed throughout the Americas from southern Canada to Patagonia. The species is a specialist carrion colonizer whose larvae feed on necrotic tissue, distinguishing it from the primary screwworm (C. hominivorax) which attacks living tissue. Adults exhibit metallic blue-green coloration with orange-red eyes and head. The species holds significant forensic importance for postmortem interval estimation and has medical-veterinary relevance as a cause of secondary myiasis in livestock and humans.