Caterpillars of Maculinea nausithous were bred in plaster nests with a colony Myrmica ruginodis ants. Sounds recording were made and the behaviour of the ants and the various stages of the caterpillars was recorded with a video-camera. As for food, caterpillars were critical and only fed on ant-larvae in a specific stage of development. During all stages (inlcuding the pupation) the caterpillars produced vibration signals. Also the butterflies vibrated during the emergence.