Host tree attacks. a extensive attacks of Saperda populnea lapponica ssp. n., on the entire stem and branches of Salix lapponum L. from Trysil: Ljørdalen, Norway b three adjacent attacks, including an exit hole, of Saperda populnea lapponica ssp. n., on a stem of Salix lapponum L. from Gällivare (Lappland), Sweden c single attacks, including exit holes, of Saperda populnea populnea (Linnaeus, 1758), on a stems of Populus tremula L. (beetles emerged at top: male, bottom: female), from Knivsta (Uppland), Sweden.