In rearing the lepidopterons leaf miner Coptodisca arbutiella Bsk. from the leaves of the Madrona (Arbutus menziesii Pursh.) at Vancouver, B. C., Mr. W. G. Mathers and Professor G. Spencer obtained specimens of a Braconid parasite which on examination proved to be an undescribed species of the genus Mirax. The species in question is very similar to Mirax ectodemiae (Roh.) and examples were submitted to Dr. C. F. W. Muesebeck who has kindly compared them with ectodemiae and has supplied additional data concerning that species.