The study was conducted to optimize the level of Black Soldier Fly Larvae (BSFL) incorporation in the abattoir sludge and food waste combination. The substrate for the study included a combination of 70 per cent abattoir sludge as the principal substrate (PS) and 30 per cent hostel food waste as the co-substrate (Co- S) for BSFL rearing. Experiments were carried out to fix the level of larval incorporation into 320 g of the substrate and to assess the nutritional qualities of the harvested prepupae. The BSFL were incorporated in four different levels in 320 g of substrate (T1: 150 mg larvae, T2: 450 mg larvae, T3:600 mg larvae and T4: 750 mg larvae). The efficiency of BSFL to feed on the substrate and get converted into biomass was evaluated for the treatment combinations. Among the different treatments, T1had significantly (p<0.001) higher mean prepupal weight and larval survivability. Hence the addition of 150 mg larvae to the 320 g of substrate was found to be optimum for BSFL biomass production.