The first reference to the existence in Argentina of the parasite that is the subject of the present article appears to be that of Messrs. Rosenfeld & Barber, who, for lack of a more exact determination, referred to it as “ el parásito díptero ” or “ el díptero.” Some time after the appearance of their publication, these entomologists sent specimens to the late Dr. Frederick Knab, who determined them as Sarcophaga ochropyga, van der Wulp ; these specimens had been reared from Diatraea saccharalis, Fabr. (sugar-cane moth borer) at the Tucumán Agricultural Experiment Station, and were later incorporated in the collection of that institution under the “ accession number 47,” and bore labels indicating Dr. Knab's identification.