In response to the increase in the demand for protein of high biological value, the breeding of insects seems to be a possible alternative source of protein. Since one of the factors that hinder the spread of insects as feed sources is the availability of cheap and healthy food matrices necessary to breed them, the aim of this study was to assess the growing capacity of the larvae of black soldier fly (Hermetia illucens), on lignocellulosic by-products. Three g of larvae of about 8 days of age (235 larvae) were bred on dry brewer's grains (Br, NDF = 61.8% DM), coffee grounds (Cf, NDF = 54% DM) or straw (St, NDF = 81% DM), in plastic containers located in the dark, at room temperature (25.3 ± 0.8 °C). For each substrate, 6 replicates were done. The breeding phase lasted 16 days, as the growing cycle was interrupted for all the containers, as soon as the first larvae had come into the pre-pupation phase. At the start and at the end of the trial the larvae were weighed and measured; their number was estimated to evaluate their survival rate and the substrate was weighed and chemically analyzed to evaluate the use of its nutrients by larvae. After verifying their normal distribution, all the data were submitted to an ANOVA model, using the substrate as fixed effect. Survival was 81.6, 80.2 and 83.6% for Br, Cf and St, respectively. The larvae achieved a length of 12.5, 11.1 and 12.0 mm, a percentage increase in weight and length of 180, 59.1 and 120% (p < 0.01) and 80.9, 60.0 and 72.8. % (p < 0.01), respectively. Larvae used 26.8, 12.1 and 8.0 DM g (p < 0.01) of substrate and led to a reduction of the substrate's NDF equal to 42.0, 5.57 and 9.28 % (p < 0.001) for Br, Cf and St. The selection of the fibrous components by larvae varied with the substrate. To conclude, the larvae of Hermetia illucens seemed to live and grow even on lignocellulosic substrates, consuming cellulose and hemicellulose but, as expected, they showed a lower and slower growth when compared to larvae grown on standard substrates such as broiler chicken feed.