Robert Owen Wahl (also Robert Owen-Wahl) attended the South African College High School in Cape Town and passed the matriculation examination of the University of the Cape of Good Hope in 1906. Continuing his studies at the South African College he was awarded the BA degree with honours in zoology by the university in 1910. Soon after graduating he was appointed as lecturer in entomology and zoology at the Grootfontein School of Agriculture, near Middelburg in the Eastern Cape. At some time during the next few years he received a scholarship which enabled him to visit the United States. He was still at Grootfontein in 1918, but by 1924 was working for the Division of Entomology of the Department of Agriculture at Potchefstroom, where he was investigating the maize stalk borer. By that time he had also worked on infestations of weevils in the grain elevators of the South African Railways. During 1929-1931 he was stationed at Standerton.
Wahl published an article on 'Karakul sheep' in the Journal of the Department of Agriculture, Union of South Africa (1920), two articles on 'The Maize-stalk borer, Busseola fusca, Fuller' in Farming in South Africa (1926, 1930), and a report on 'The importance of nest structure in the control of certain South African Termites with cyanogas calcium cyanide' (with A.R. Powell, 1927). He became a member of the South African Association for the Advancement of Science in 1913 and a foundation member of the Entomological Society of Southern Africa in 1937. He was married to Annie Lillian ('Mitsie') Brent, with whom he had a son and two daughters.