Black Soldier Fly larvae (BSFL) are recognized to be rich in macronutrients, especially proteins and lipids. Hence, BSFL have been more and more used for biowaste recycling to create value-added products. They especially make a suitable alternative source of protein for animal feed. BSFL also contains micronutrients such as vitamins and minerals. Recently it was demonstrated by our group that BSFL can bioaccumulate interesting concentrations of fat-soluble vitamins and carotenoids from the substrate they are reared on. This suggests that BSFL could bioaccumulate valuable concentrations of other phytochemicals. Among all the phytochemicals contained in plants, polyphenols hold a special place because numerous studies have suggested that they can have beneficial effects on health, whether in humans or in livestock. But no study has been dedicated to assess whether some polyphenols can significantly bioaccumulate in insects reared on polyphenol rich substrates. BSFL are commonly raised on wheat bran, rich in ferulic acid (FA) and caffeic acid (CA), compounds of nutritional interest due to their health effects, both on livestock and humans. The aim of this study was to determine if they can also bioaccumulate interesting quantities, from a nutritional point of view, of these phenolic acids. We therefore raised larvae on this substrate and measured the concentration of these compounds in larvae. We observed extremely low concentrations of FA in the larvae and we did not detect CA. Indeed only 1% of FA concentration observed in wheat bran was found in BSFL. the FA quantity measured in a whole larva was 5 times inferior to the theoretical quantity in just the BSFL gut filled with wheat bran. It is therefore clear that the larvae degraded almost all the FA present in the wheat bran. In conclusion, this study suggests that BSFL does not bioaccumulate FA and probably CA. On the contrary, it seems that the larvae catabolize it very efficiently, which suggests that they have a biochemical pathway dedicated to this elimination.