comparative morphology of the spermathecae of some species of chrysomya robineau-desvoidy and cochliomyia townsend (diptera, calliphoridae). little is known about the morphology of the chitinized structures of the spermathecae of the calliphoridae. in this work, the spermathecae of chrysomya albiceps wiedemann, 1819, c. megacephala fabricius, 1794, cochliomyia macellaria fabricius, 1775 and c. hominivorax coquerel, 1858 are described and illustrated. the occurrence in one species of four spermathecae, an atypical form for blow flies, was recorded for the first time. the analysis of these structures will allow a better understanding of this group as well as provide taxonomic characters for future phylogenetic studies.