Life cycle of A. corruptrix (Schlechtendal, 1870) is treated and corrections to previous experiments are discussed. A new sexual form for A. corruptrix is herein described, while A corruptrix forma larshemi is considered a valid species and for taxonomical reasons is renamed as Andricus improprius n. stat & n.sp, only known by the sexual form, and not linked with A. corruptrix. Lectotypes for A. improprius n. stat & n. sp.(= A. larshemi not available) are also designated.