Millidge conducted research at the
American Museum of Natural History, where he published numerous taxonomic studies on linyphiid spiders. His work focused particularly on the subfamily
Erigoninae, and he published a comprehensive series on the erigonine spiders of North America in the
Journal of Arachnology between 1980 and 1987. His taxonomic work included detailed revisions of several genera, including studies of
Walckenaeria,
Eperigone,
Spirembolus, and
Disembolus. Millidge also worked extensively on
South American linyphiid fauna. His 1985 study described numerous species from Chile and other South American regions, and his 1991 monograph on South American linyphiids was published in the
Bulletin of the American Museum of Natural History. ==
British Spiders==