The Japanese beetle (Popillia japonica) is a beetle about 1.5 cm (0.6 inches) long and 1 cm (0.4 inches) wide (smaller in Canada), with shiny copper-colored elytra and a shiny green top of the thorax and head. It is not very destructive in Japan, where it is controlled by natural enemies, but in America it is a serious pest to rose bushes, grapes, crape myrtles, and other plants. It is a weak flyer and drops several centimeters when it hits a wall. Japanese beetle traps therefore consist of a pair of crossed walls with a bag underneath, and are baited with floral scent, pheromone, or both. However, studies done at the University of Kentucky (MANAGING ADULT JAPANESE BEETLES) suggest that traps attract more beetles than they actually trap, thus causing more damage than may have occurred were the trap not used.
Japanese beetles have a curious, identifying defense: they lift their hind legs up in the air, even when simply approached. These hind legs are spiny, and the behavior is probably intended to ward off predators.