Abstract
The acoustic behaviour of four Aphodius dung beetle species from the Pacific Northwest of the USA was investigated. Male Aphodius produce substrate vibrations when they meet a conspecific female in a dung pat. The temporal structure of the substrate vibrations and the stridulatory organs are described. The vibrations are species-specific songs that are emitted during courtship. The stridulatory organ is of the abdomino-alary type in the investigated species. Morphological differences with regard to the detailed structure are present.