I am not aware that any parasites have ever been reported as attacking the larvæ of Danais archippus of the maggots of Anthomyia raphani. However that may be, it will be interest to the readers of the Entomologist to know that last fall I obtained from a single chrysalis of D. archippus over fifty speciments of a new species of Pteromalus. The parasites came forth September 13, the chrysalis having been brought into the laboratory a few days before, and inclosed with a bell-jar. Specimens were sent to Mr. L.O. Howard, who has since described the species and given it the name of Pteromalus archippi.