The article presents the results of a study to determine the degree of biodegradability of feather raw material as a food substrate for clothing moth caterpillars and brown carpet beetle larvae and shows that this indicator depends on the stage of development of ceratophagous insects. The paper aims to assess the degree of biodegradation of feather raw material as a food substrate for the caterpillars of clothing moths, Tineola bisselliella (Humm.), and the larvae of brown carpet beetles, Attagenus smirnovi Zhant. Once we used organoleptic examination to assess nutritional suitability of feather raw material for ceratophagous insects and analyzed its physical and chemical properties, we found that feather raw material is a favorable breeding ground for ceratophagous insects, as evidenced by its characteristics. As we compared the biodeterioration effect of clothing moth caterpillars and brown carpet beetles on untreated feather raw material, we found that samples affected by clothing moth caterpillars bore the most damage 28 days after the experiment began, i.e., 9.64%, while brown carpet beetle larvae affected 2.13% of the sample over that period, a direct consequence of the brown carpet beetle larvae development cycle.