The Japanese beetle, Popillia japonica (Newman, 1841) (Coleoptera: Scarabaeidae), is a highly polyphagous and destructive scarab with over 300 reported host plants in ornamental plants, agriculture, and forestry (Fleming, 1972). In 2014, this invasive beetle was seen for the first time in Northern Italy, and 2017 in Ticino. Since then, individual adult beetles have also been found in Basel and Neuendorf, and in Southern Germany. The aim of this project was to investigate the potential of biological control using Swiss strains of insect parasitic nematodes. First laboratory experiments, endemic strains of Steinernema carpocapsae and S. feltiae have been found to cause high mortality rates (60% to 80%). In several pot experiments, apart from endemic S. feltiae strains, S. bicornutum and Oscheius sp. were found to be the most virulent indigenous EPN strains, with efficiency rates ranging up to 100% mortality. Commercial strains induced mortalities of similar magnitude, with Heterorhabditis downesi and H. bacteriophora showing the highest efficiency among them (from 85% to 100%), while commercial strains of S. feltiae and S. carpocapsae resulted in between 35% and 90% mortality, and 85% larval mortality. This study shows that indigenous Steinernema strains have a high potential as biological control agents against larvae of the invasive insect P. japonica in Switzerland.