A chemically defined diet (Ceratitis capitata #2 diet) for rearing adult Ceratitis capitata (Wiedemann), the Mediterranean fruit fly, was developed by adding vitamin B₁₂ 0.024 mg, ascorbic acid phosphate (vitamin C) 3.68 mg, vitamin D 12 mg, vitamin E 8.16 mg, inositol 243 mg, choline chloride 120 mg, cholesterol 40 mg, nicotinic acid 1.64 mg, sugar 6 g, agar 400 mg, and water 7 ml to each 50 g meridic larval diet (C. capitata #1). The C. capitata #2 diet was prepared in two forms, agar and liquid and both showed comparable performance to the standard diet but the agar diet is considered to be the best diet tested. Adults reared on the agar diet produced more eggs than those on a protein hydrolysate-sugar (1:3) diet. Flies fed on diets lacking nutrient groups, such as the 10 essential amino acids, eight nonessential amino acids or the combination of cholesterol, inositol, and choline, produced fewer eggs. Those fed on the diet without the 14 vitamins, cholesterol, inositol, or choline produced a normal number of eggs. Increasing the sugar content in the diet did not affect egg production or hatch. Sugar concentration in the diet influenced fly survival.