Notes sur les hypopes du genre Horstia Oudemans, 1905 (Acari, Acaridae), phoretiques sur les Hymenopteres. - The genus Horstia Oudemans, 1905 (Acari, Acaridae) is revised. It is divided in two subgenera: Horstia s. str. with six species, among which one new (H. rwandae), from the Old World, and Amhorstia subg. n. with four species ali from the New World. H. scutata Fain, 1974 is synonymized with H. glabra Vitzthum, 1920. A new subfamily, Horstiinae is created for Horstia Oudemans, 1905. lt includes a second genus Ceroglyphus Vitzthum, 1919.