Adults feed on the foliage and fruits of hundreds of species of trees, shrubs, vines, and vegetable crops leaving behind skeletonized and large, irregular holes in leaves.
The grubs develop in the soil, feeding on the roots of various plants and grasses.
The adult Japanese beetle is a little less than 1/2 inch long and has a shiny, metallic-green body and bronze-colored outer wings. The beetle has six small tufts of white hair along the sides and back of its body under the edges of its wings. The males usually are slightly smaller than the females. You are most likely to see the adults in late spring or early summer.
Traps for Japanese Beetle Control
Several traps using a floral lure and pheromone sex attractant are available. These traps are effective for Japanese Beetle control under certain conditions. The traps have been demonstrated to be effective in reducing damage and populations only when landscapes are isolated from other Japanese beetle populations or when mass trapping is used.
The lures used in the traps can actually multiply your infestation of beetles by drawing them in from the surrounding area. Your Yard or Garden could actually become "The Red-light district" for these varmints. Susceptible plants in the vicinity of traps may suffer much more damage than if no traps are used at all.
Pesticides Registered for use in Japanese Beetle Control
Pyrethroids and carbaryl based pesticides provide a few weeks of protection from Japanese Beetles. Repetitive applications are necessary roughly every 5 to 10 days as theses chemicals break down in nature quickly and their effect diminishes exponentially. Pyrethin and pyrethoids are a bio-pesticide made from chrysanthemum flower extracts and are believed to be the most effective against Japanese Beetles. Along with piponeryl butoxide which is another naturally derived compound which has no pesticidal properties of its own but when combined with pyrethins or cabaryl it enhances their potency.
Carbaryl is sold under brand name of Sevin or simply Carbaryl.
The following products are registered for use by Home Gardeners against Japanese Beetles.
Susceptible plants should be thoroughly treated. Applications should be repeated during the adults flight period. Follow label directions and avoid spraying under wet or windy conditions or when bees and other pollinators are present in any numbers. Be sure the insecticide is registered for use on the plant you intend to spray. For edible plants note the number of days that must be observed from the date of the final application till harvest.
Organic Japanese Beetle Controls
Neem Oil Deters, but does not kill Japanese Beetles
Dormant Oil Sprays, garlic oil, hot pepper or citrus sprays are generally ineffective for Japanese Beetle Control.
Raspberries are said to deter Japanese beetles but this is not proven.
Japanese Beetle Control of Grubs ~ Larvae Stages
Grubs are best controlled when they are small and actively feeding near the soil surface, usually mid to late summer. Control of grubs in late-fall or early-spring is difficult, at best, because the grubs are large and are generally not feeding.
Milky Spore is very effective in reducing Japanese Beetle populations, it is not harmful to beneficial insects, birds, bees, pets or man. In fact the only thing it has any effect on are grubs. It must be used when the grubs are actively feeding in warm soil to be effective. If the soil is cooler than 65 F the spores will be inactive and ineffective.
The spores germinate inside the grubs, and multiply rapidly in their blood. As they multiply in the blood, infected grubs survive for 7-21 hours after their blood has become loaded. As the grub carcass decomposes, it releases billions of new spores.
Other biological controls include the use of existing natural predators.Nematodes have demonstrated to be somewhat effective in Japanese Beetle control during the grub stage particularly as part of an integrated pest management regimen.
Milky spore can be used in conjunction with nematodes as the spores have no effect on them. Apply the nematodes when the white grubs are small. Water thoroughly before and after applying the nematodes.
The nematodes enter the host through body openings or by penetration of the body wall. Once inside they release a bacterium which kills the host within 48 hours. The nematodes continue to reproduce and the offspring begin to seek out new host material. Beneficial nematodes are a totally safe biological parasitic insect control.
Japanese Beetle in The Urban Landscape
Japanese Beetle Control
Featured Creatures ~ Japanese Beetles