Japanese beetle: Biology and ecology

Japanese beetles and  injury: Japanese beetles, Popillia japonica, and injury to a soybean leaflet. (Photo Marlin E. Rice)Japanese beetles and injury: Japanese beetles, Popillia japonica, and injury to a soybean leaflet. (Photo Marlin E. Rice)

The Japanese beetle, Popillia japonica, was accidentally introduced into the United States in the early 1900s on horticultural nursery stock in 1916 in New Jersey(Ratcliffe 1991, Borrer et al. 1992). Since that time it has been expanding westward. This beetle has a large and diverse host range including woody trees such as elms to annual crops such as corn and soybean and even golf course greens. The Japanese beetle apparently will feed on about 300 plant species (Ratcliffe 1991)!

Japanese beetles have one generation per year and overwinter as larvae. Eggs are laid about 5-10 cm into the soil and take roughly two weeks to hatch (Ratcliffe 1991). The larvae feed on roots and pupate in earthen cells.