Entomologist, specializing in Hymenoptera. After becoming a member of the Academy, he joined with James Ridings and George Newman to found the Entomological Society of Philadelphia, in which he held office thru 1924. One of the first editors of the Practical Entomologist and establisher of the Entomological News. His memoir of Thomas B. Wilson and his history of the American Entomological Society are outstanding historical treatises. His many years of scientific study culminated in his, Synopsis of the Hymenoptera of North America.

His annotations are found in his personal copy of Provancher's Les Ichneumonides de Quebec, 1873-74 and in the Departmental copy of R. Osten Sacken's Catalogue of Diptera. Penciled checks by Cresson record the species in the Academy's collection.