This study focused on the use of an important micronutrient, vitamin D3 for control of pest insects as environmentally sound alternative management. Vitamin D3 which is a lipophilic vitamin at nutritionally reguired doses not only have important physiological roles but also has a toxic effect at high dietary concentrations. The first instar larvae of Drosophila melanogaster (Meigen) (Diptera: Drosophilidae), which is an important pest model organism were reared on artificial diet containing vitamin D3 concentrations of 5.0, 20, 80, 320, 1280 and 2560 mg/L to adult stage in laboratory condition. The effects of this vitamin on developmental stages of the insects were microscopically observed. Morphometric changes depending on increased vitamin D3 concentrations in the developmental stages from larvae to adults were recorded by microscobic and personal observations. Vitamin D3 at increasing concentrations (especially 80-2560 mg/L) in larval diet increased melanization in abdominal region of the insect. This study refers vitamin D3 can play a fortifying role in development as a nutritional additive at low concentrations, or can be used as an insecticide at high concentrations due to its possible toxic effect.