The pink bollworm, Pectinophora gossypiella (Saunders), was aseptically reared to determine dietary B-vitamin requirements. Lack of anyone of the following vitamins in a casein medium resulted in 100% larval mortality: Calcium pantothenate, folic add, nicotinamide, pyridoxine, riboflavin, and thiamine. No larvae matured in the absence of biotin in amino acid medium. In a medium of wheat germ ... [Show full abstract] without added nicotinamide or calcium pantothenate, complete larval mortality occurred. Larval development with or without vitamin B12 in 3 different media was similar. Quantitative vitamin requirements on casein medium for calcium pantothenate, nicotinamide, riboflavin, thiamine, pyridoxine, and folic acid were 0.40, 0.20, 0.050, <0.050, 0.0125, and 0.0125µ/g 100g of medium, respectively. Quantitative biotin requirement on amino acid medium was 1 µg /100g of medium.