Efficiency of Japanese beetle (Coleoptera: Scarabaeidae) traps in reducing defoliation of plants in the urban landscape and effect on larval density in turf.
Although attractant traps are commonly used to protect ornamental and garden plants from defoliation by Popillia japonica, neither the usefulness of this practice nor its effect on larval densities around traps has been determined. In experiments on a golf course and in home landscapes in Kentucky in 1984, single traps positioned 3.1 or 9.3 m upwind or downwind from test plants (Vitis sp.) failed to reduce defoliation when compared with that occurring on plants without traps. In fact, defoliation was nearly always greater when a trap was present. Surrounding a plant with traps, each 9.3 m away, resulted in >90% defoliation within 30 h. Larval densities in turf were not significantly altered in the vicinity of traps.