R.W.E. Tucker was appointed as assistant in arachnology in the Department of Entomology of the South African Museum, Cape Town, in 1914. During the next seven years he collected arachnids (scorpions, spiders, mites, ticks, etc.) and insects very widely in the Cape Province, Transvaal, Namibia, Botswana and Zimbabwe. Among others he contributed ants from Namibia, the Transvaal, Zimbabwe and the Cape Province to the museum's collections. He also rearranged the whole arachnid collection and published several papers: 'On some South African Aviculariidae (Arachnida)' (1917), 'On some new South African spiders of the families Barychelidae, Dipluridae, Eresidae, Zodariidae, Heracliidae, Urocteidae, Clubionidae' (1920) and 'The Drassidae of South Africa (Arachnida)' (1923) in the Annals of the South African Museum (Vol. 17, Part 2 and Part 5; Vol. 19, Part 2).
In 1919 Tucker, S.H. Haughton* and K.H. Barnard*, on the instructions of L.A. Peringuey*, director of the South African Museum, excavated Montagu Cave in the Western Cape.
Tucker left the museum in 1921 to join the Division of Entomology in the Department of Agriculture. By 1924 he was working on mites, which were a serious pest in the deciduous fruit orchards of the Cape Province. He described 'The black sand mite: Penthaleus destructor, n. sp.' (1925) and 'Some South African mites' (1926) in the Entomology Memoirs of the Department of Agriculture (No. 3, pp. 21-36 and No. 5, pp. 1-15). With H.K. Munro, E.P. Felt and C.H. Curran he also described New African gall midges (SA Department of Agriculture, 1926, 48 pp.) Around this time he left South Africa to take up an appointment as chief entomologist in the Department of Scientific Agriculture in Barbados. He appears to have remained there for the rest of his career. His work and publications during this period had to do mainly with the biological control of the sugar cane pest Diatraea saccharalis.