The red necked longhorn beetle (Aromia bungii), globally known as an insect pest damaging Rosaceae, was found in Osaka Prefecture in 2015. The occurrence pattern was examined of the species on their host trees (Rosaceae) in Osaka Prefecture between 2015 and 2017. The number of damaged trees increased over years and some trees seemed to have died due to the feeding of the long horn beetles. More damages were observed in ornamental cherry trees with larger trunk (in perimeters at the root). When compared among similarly damaged trees of different size, larger trees were found less vulnerable and smaller ones tended to wither easily.The highest damage position of each tree was measured, and in most trees, the positions were lower than 2 m above the ground. Also, they were higher in those trees with longer period of damage.