Several components of an internal kairomone were identified inside eggs of the host, Adoxophyes sp. (Lepidoptera:Torticidae), that releases egg deposition of the egg-larval parasitoid, Ascogaster reticulatus Watanabe (Hymenoptera:Braconidae). Pupal hemolymph with the same activity as an internal host egg kairomone was used as a convenient test sample. Heat-treated pupal hemolymph was chromatographed on a Sephadex G-25 column. Each fraction was bioassayed and reacted with ninhydrin. The active fractions were ninhydrin-positive. Each fraction was placed onto an amino acid analyzer, which showed that the amino acids were most abundant in active fractions. Among 22 amino acids, alanine, arginine, glycine, histidine, isoleucine, methionine, proline, serine, tryptophan, and valine were active. The mixture of these active amino acids was as the egg-mass homogenate at the same ratio and concentration, suggesting that the most important component as the kairomone in a host egg is the mixture of several amino acids. none