Abstract: The Japanese beetle (Popillia japonica) is a scarab (Scarabaeidae) that originates from Japan. It was accidentally introduced into the USA, the Azores and recently to northern Italy. Whereas the Japanese beetle is not a serious pest in its natural range, it causes severe damage in the areas where it was introduced. Adults feed on leaves, flowers and fruits of many cultivated plants while larvae mostly damage turf and pastures.In the USA, mainly insecticides are used to control the Japanese beetle. However, a range of biological alternatives is being investigated. In 2017 and 2018, Agroscope tested the virulence of different Beauveria and Metarhizium strains against adults and larvae of P. japonica in a quarantine lab. The tested strains are native to Switzerland and were isolated from related scarab beetles. Mortality rates of up to 100% were achieved for adult beetles within a period of 7 dpi only, whereas mortality rates of larvae were between 50 and 100% after 42 dpi. While mortality correlated with dosage, sporulation on infected cadavers did not.