The effect of host diet on the immature developmental time, fecundity, sex ratio, adult longevity, and size of Apanteles galleriae Wilkinson, a koinobiont, solitary, and early instar larval endoparasitoid of the lesser wax moth, Achroia grisella (F.), was investigated. All experiments related to the effect of diet were conducted at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 12:12 (L:D) h. The experiments were conducted by supplying hosts with three types of natural food (blackened, dark yellowish, and pure comb). The change in the type of host diet from blackened, to yellowish, and to pure comb prolonged immature developmental time, shortened the life span, increased sex ratio in favor of males, and reduced fertility and adult size of parasitoid species. The first adult eclosion occurred at 25, 30, and 52 d for males and 27, 33, and 54 d for females, with blackened, dark yellowish, and pure comb, respectively. The mean production of progeny per female parasitoid for each diet was 105.09, 45.49, and 0.46 (n = 30). Males lived an average of 43.46, 14.52, and 5.75 d and females lived an average of 40.86, 16.8, and 10 d in relation to host diet changes. Parasitoid length varied considerably with 2.84, 2.5, 2.2 mm, and 2.51, 2.27, 1.94 mm for females and males, respectively. Of the three kinds of natural food, the first was determined to be the most optimal diet for the parasitoid species.