An annotated catalog of type material of the genus Aphytis Howard (Hymenoptera: Aphelinidae) in the collection of the Entomology Research Museum, University of California, Riverside, California, USA (UCRC) provides information on 75 valid species. Curation of the UCRC Aphytis slide collection involved remounting 7,390 specimens from Hoyer's medium into Canada balsam (a single specimen per each slide). This included 7,292 specimens that were remounted, labeled, and databased and 98 specimens that were remounted and labeled but not databased (the types of the South African species received on loan from the South African National Collection of Insects, Plant Protection Research Institute, Pretoria, South Africa). Among these are 309 primary type specimens (i.e., holotypes, syntypes, lectotypes, and neotypes) belonging to 51 nominal species, 2,473 secondary type specimens (i.e., paratypes, allotypes, and paralectotypes) of various nominal species, and 4,608 nontype specimens of many species of Aphytis from more than 50 different countries. Numerous nomenclatural and other mistakes (such as improper or coded labeling) in the treatment of the type specimens of the Aphytis species are corrected; several primary types are returned to the appropriate depositories, and many remounted secondary types are donated to other major taxonomic collections of Aphelinidae. Lectotypes are designated for A. africanus Quednau, A. coheni DeBach, A. cylindratus Compere, A. equatorialis Rosen and DeBach, A. fisheri DeBach, A. holoxanthus DeBach, A. immaculatus Compere, A. lepidosaphes Compere, A. lingnanensis Compere, A. melinus DeBach and A. taylori Quednau.