The composition of the protective secretion of the seven-spot ladybug Coccinella septempunctata L. (Coleoptera, Coccinellidae) has been studied by the methods of high- and low-resolution mass spectrometry. By determining the complete genetic link between the ions of a sample of the secretion by the methods of metastable defocussing and the direct analysis of daughter ions (DADI) the presence of the molecular ions of eight substances contained in the secretion has been shown. These components of the secretion have been identified as squalene, cholesterol, cholesta-3,5-diene, palmitic acid, and the alkaloids coccinellin, precoccinellin, and propylein, and a probable structure has been proposed for a base C13H16N. © 1982 Plenum Publishing Corporation.