Laboratory experiments were conducted to study the effect of three diets on some biological aspects when the black earwig, Chelisoches morio feeds on newly deposited eggs, and first larval instar of the cotton leaf worm, ground cat's dry food and newly deposited eggs of the red palm weevil. Results indicated that the eggs incubation periods of Ch. morio were 6.62, 7.33 and 9.00 days by rearing on the three diets, respectively. A single mated female deposited 95.62, 80.93 and 120.03 eggs per female by rearing on the three diets, respectively. The hatchability percentage among the deposited eggs reached 87.11, 88.22 and 86.11%, respectively. The longest duration was that of the 4^th instars (24.7 days), when feeding took place on RPW eggs, while the shortest period was 7.2 days, for the first instar by feeding also on RPW egg. The sex-ratios of females (%) were 60, 56 and 64% females, respectively. The pre-oviposition period of the females was 30.69, 35.27 and 33.01 days, while the oviposition period was 67.54, 56.06 and 55.03 days, for the same treatment, respectively. The post-oviposition was 52.23, 31.00 and 46.00 days, respectively. Nymphs of the 4^th instar fed on 329.8 eggs of RPW, being the highest voracious feeder as compared to the first three nymphal instars which consumed the means of 11.1, 65.9 and 166.0 individuals, respectively. The feeding capacity of adults was 1223.6 for males and 1357.4 for females indicating that females were more voracious than male. The study recommends feeding on RPW eggs in mass rearing of the black earwig for biological control.