In its native Japan, where the Beetle's natural enemies keep its populations in check, the Japanese Beetle (Popillia japonica) is not a serious plant pest.
But, in the United States, the beetle entered without its natural enemies and found a favorable climate and an abundant food supply. By 1972, beetle infestations had been reported in 22 States east of the Mississippi River and also in Arkansas, Iowa, and Missouri. Since then, the pest has spread to Southern and Western States, but tough regulations and careful monitoring have prevented its establishment there. Without its natural checks and balances, the Japanese beetle has become a serious plant pest and a threat to American agriculture.
Today, the Japanese beetle is the most widespread turf-grass pest in the United States. Efforts to control the larval and adult stages are estimated to cost more than $460 million a year. Losses attributable to the larval stage alone have been estimated at $234 million per year—$78 million for control costs and an additional $156 million for replacement of damaged turf.