Boise, ID - A new invasive insect, the Japanese beetle (Popillia japonica), recently was detected in Idaho in both Ada and Kootenai counties. The Japanese beetle was first introduced to the United States in 1916 in plants imported from Japan. The insect is approximately ½-inch long, a shiny metallic green with copper-brown wing covers.
Adult Japanese beetles feed on trees, rose bushes, stonefruits and many garden and field crops leaving holes and skeltonized leaves. The larvae, or grubs, live under the soil surface and destroy patches of turf by feeding on roots of grass.