SummaryThis publication presents new results concerning the construction of cobwebs and the sexud behaviour of spiders (Araneae). The studied spiders:Crespmatoneta mutinensis, Drapetisca socialis, Lithyphantes paykullianusandCyrtophora citricoladiffer from their relatives either because of their beheviour or their morphology. It is demonstrated that the exact knowledge of the behaviour of these spiders is important for their classification. Therefore this publication is a contribution to the discussion about the importance of ethology for the zoological systematics.