The excreta of clothes moth larvae (Tineola) bred on a� standard undyed woollen fabric, the black carpet beetle (Attagenus) living on wool, and the potato moth (Gnorimoschema) feeding on potato tubers, have been examined. Water-soluble nitrogen constitutes most of the total nitrogen in both Tineola and Attagenus excreta. The fraction of this water-soluble nitrogen ontributed by uric acid or its salts is high in Tineola, but considerably lower in Attagenus. Up to 3 per cent. urea and an appreciable quantity of ammonia are also present.