Doctor of Science, Potchefstroom U.Christian Higher Education, Potchefstroom, South Africa, 1963.
Citrus estate acarologist Consolidated Citrus Estates PTY Ltd, Zebediela, Potgietersrust District, South Africa, 1964—1966. University lecturer, senior lecturer and associate professor in zoology University of the North, Sovenga, 1966—1981, professor in zoology Qwaqwa Sattelite Campus, dean science faculty, member senate Phuthaditjhaba, 1982—1996. Affiliated researcher American Red Cross, Pretoria, South Africa.
Affiliate researcher department zoology and entomology University Free State, Bloemfontein, since 2008.
Chairman Pro Artibus Choir, Pietersburg, South Africa, 1972—1975. Church elder Dutch Reformed Church, Pietersburg and Harrismith, since 1969.
Married Martie Van Jaarsveld. Children: Maarten Willem, Margaretha Elizabeth, Klara Cronje-Den Heyer, Martie Johanna Jacobs -Den Heyer.