The New World screwworm Cochliomyia hominivorax (Coquerel) is an important parasitic insect pest in Neotropical regions. NewWorld screwworm myiasis is caused by the larval stage of the fly infesting tissues of warm-blooded vertebrates. This species represents a serious threat to the livestock sector across its current distribution, which includes part of the Caribbean and all of South America (except for Chile). Knowledge of the extent and distribution of genetic variability of C. hominivorax is of great interest for the description of populations and for contributing to future strategies of control. 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