Japanese beetles are back in town, protect your trees
Posted by Sue Bennett
Because these obnoxious, metallic green and brown beetles feed on over 250 different species of plants (roses, lindens and maples are favored), high expectations are given to traps to help save the day. Japanese beetle traps are very effective in attracting and trapping adult Japanese beetles, but they are ineffective in protecting your susceptible trees and shrubs from Japanese beetle feeding damage.
This seemingly contradictory answer requires an explanation. Japanese beetle traps, sold at most garden center outlets, usually contain two separate, chemical lures. One lure is a feeding attractant that attracts both male and female beetles. The second lure is a pheromone that attracts male beetles. These lures work very well in attracting hundreds, even thousands of adult beetles toward the trap.
Therein lies the problem. Many adult beetles are attracted into the area around the trap, but they do not necessarily get caught inside the trap. Susceptible plant species located nearby can be more heavily damaged than if the traps were not used at all. This can be true even if the trap is full of captured adults.
If you would like to experiment with Japanese beetle traps, be sure to locate them as far away as possible from the plants you are trying to protect. Placing a trap in the middle of your rose garden, for example, is just asking for trouble.
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Photo credits: Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org (left and bottom right), Shimat Joseph, University of Georgia, Bugwood.org (top right)