In this study, we report on in vitro incorporation experiments of several labelled fatty acids in the ladybird alkaloids coccinelline (Coccinella 7-punctata), adaline (Adalia 2-punctata), and harmonine (Harmonia axyridis). The obtained results clearly indicate that stearic acid is the precursor of coccinelline and harmonine, whereas myristic acid is at the origin of the carbon skeleton of adaline.