Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Experiments using the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were conducted to determine the mortality of males and females and the ovipositing ability of females fed on two diets. The sugar diet consisted of 5: 1 sugar:protein and the protein diet consisted of 5:1 protein: sugar. Dilutions of 80%, 60%, 40%, 20% and 10% with water of both diets were also provided to the flies. Female longevity was shorter than male longevity. There was no difference in female longevity between fruit flies fed on the two diets. However, males fed on the sugar diet lived longer than those fed on the protein diet. More eggs per female per day were laid by those fed the sugar diet than by those fed the protein diet. There were no differences m oviposition between flies fed on the different concentrations of the two diets. / AFRIKAANSE OPSOMMING: Proewe met die Mediterreense vrugtevlieg, Ceratitis capitata (Wiedemann), is uitgevoer om die mortaliteit van die mannetjies en wyfies, asook eierlegging van wyfies wat met twee verskillende diëte voorsien is, te bepaal. Die onderskeie diëte het uit 'n mengsel van proteïen en suiker (5 dele suiker en 1 deel proteïen) en (5 dele proteïen en 1 deel suiker) bestaan. Verdunnings van 80%, 60%, 40%, 20% en 10% is van die onderskeie diëte gemaak en aan die vlieë voorsien. Daar was geen verskil in die lewensduur van wyfies wat op die twee diëte gevoed is nie. Mannetjies wat op die oorwegende suiker dieët gevoed is, het langer as dié wat op die proteïen dieët gevoed is, geleef. Vlieë wat op die suiker dieët gevoed het, het regdeur 'n hoër gemiddelde daaglikse eierlegging per wyfie as dié wat op die proteïen dieët gevoed het, getoon. Geen noemenswaardige verskil in eierlegging vir vlieë wat op verskillende konsentrasies van die twee diëte gevoed het, is gevind nie.