Thorough coverage of the plant is important. Japanese beetle traps are more effective in luring beetles to an area than they are at actually catching them. They are not considered effective for control unless everyone in the neighborhood has one. Hand picking adults from infested plants and dropping them in soapy water is effective but very labor intensive. It is a constant battle as more beetles appear after others are removed.
Japanese beetles do have several natural enemies.
Birds, skunks, moles and shrews will readily eat large amounts of grubs. Two species of parasitic wasps and one type of parasitic fly also help to reduce populations. Trade or brand names are used for information only. The University of Georgia College of Agricultural and Environmental Sciences does not guarantee or warrant published standards on any product or variety mentioned, nor does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.