Horticulture - Managing Japanese beetles
Source: Lee Townsend, UK Japanese beetles feed on over 300 species of plants including rose, birch, linden, crabapple, grape, Virginia creeper and buckeye. Adults are approximately 7/16-inch long and metallic green with coppery wing covers. They feed on leaves, flowers and wounded or mushy fruit.
Adults often feed on the green material on the upper surface of the leaf leaving a lacelike or “cellophane” appearance. Most feeding activity occurs over a four to six-week period, though individual beetles usually live about 30 to 45 days.
Options for homeowners:
• Exclusion - Highly valued plants, such as roses, can be protected by covering them with cheesecloth or other fine netting during the peak of beetle activity.
• Hand Removal - Keeping Japanese beetle numbers low forestalls the arrival of more beetles and subsequent rapidly increasing damage. Reducing the number of feeding beetles reduces the release of aggregation chemicals that attract other beetles in the area.
• Japanese Beetle Traps - Research conducted at the University of Kentucky showed that the Japanese beetle traps attract many more beetles than are actually caught. Consequently, susceptible plants along the flight path of the beetles near the traps are likely to suffer much more damage than locations where traps are not used. In most landscape situations, use of Japanese beetle traps probably will do more harm than good. If you experiment with traps, be sure to place them well away from gardens and landscape plants.
• Insecticides - Insecticides containing carbaryl or pyrethroids can provide relatively long term protection of plant foliage. However, these insecticides are highly toxic to pollinators and must not be used on flowering plants or where spray drift can carry droplets to blooming plants. Other insecticides labeled for Japanese beetle control in the home landscape include:
• BeetleJUS! And BeetleGON are Bt (Bacillus thuringiensis galleriae) products labeled as foliar sprays for use on ornamentals and vegetables to control Japanese beetles and other beetle pest species. BeelteJUS! must not be applied within 300 feet of any habitats of threatened or endangered Lepidoptera (i.e., moths or butterflies) or Coleoptera (i.e., beetles). This produce does not have a bee warning on the label. • Pyola Insect Spray contains pyrethrins and canola oil. It is labeled for use on a range of fruit and nut trees, flowers, vegetables, landscape ornamentals and shade trees. This product is highly toxic to bees exposed to direct treatment on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds while bees are actively visiting the treatment area. • PyGanic (available as a 1.4% or 5 percent EC) contains pyrethrins. It also is highly toxic to bees and has the same environmental warnings as Pyola.