In 1916, the Japanese beetle (Popilia japonica) was found in New Jersey, USA, an attractive invasive species from its native Japan, sporting iridescent brown elytra (wing coverings) and green head and thorax. Although not a pest in Japan, populations of the scarab beetle rapidly expanded in North America where it was free from predators and parasites, and spread west across the continent. Both the adult and larval form of this insect is a pest. The beetles tend to feed as a group, and cause severe damage to plants as together they skeletonize leaves, and consume flowers and fruit of a very broad number of host plants. The white, C-shaped larvae hatch out of eggs laid in the soil and do damage especially to grasses and seedlings, as they feed steadily on root systems. By late summer they reach full-size, then go dormant underground for the winter. Grubs are especially damaging to turf grasses in golf courses, cemeteries, and other lawns. They emerge in early June as beetles. Food- and hormone- containing traps for beetles are commercially available, however, because they attract beetles so effectively they may in fact attract more beetles to an area than they can remove. Physically removing beetles helps rid this pest as they like to cluster. Japanese beetles are susceptible to several bio-control agents; bacteria causing milky spore disease (Paenibacillus popilliae) and an insect-attacking nematode (Heterorhabditis bacteriophora.) are effective and can be obtained for use against this beetle. There also are insecticides labeled for use against Japanese beetles.

(CABI 2011; Cranshaw 2007; Potter, Potter and Townsend 2006; Wikipedia 2011