If Japanese beetles are wrecking your garden, you are not alone. This invasive species consumes the leaves, fruit, and flowers of more than 250 different crop and ornamental plants. Before you resort to environmentally-damaging pesticides, you may be able to rid your yard of Japanese beetles by attracting the beetle's natural predators to your yard, and by avoiding the plants that Japanese beetles prefer the most.
Birds
Attracting insectivorous birds to your yard can be as simple as putting out a birdbath and possibly a seed-feeder and nest-boxes near infested plants. Starlings are the best known beetle-killers, as they consume both the grubs and the adult Japanese beetle. Meadowlarks and blackbirds, crows, and grackles eat only grubs, while catbirds, robins, and cardinals occasionally eat grubs and enjoy adult beetles. Bobwhites, woodpeckers, eastern kingbirds, blue jays and sparrows also eat Japanese beetles. Purple martins are easily attracted to man-made nests and eat the grubs of the Japanese beetle. It is helpful to the birds if you turn the soil in autumn, exposing the larva. As for domestic birds, both chickens and guinea fowl will eat Japanese beetles.
Animals and Insects
Shrews, skunks and moles feed on Japanese beetle grubs, and are frequent visitors to suburban gardens. Spiders, ants and other predatory insects eat large numbers of beetle eggs in the soil even before they hatch. In this manner, eschewing use of pesticides is actually helpful in eliminating beetles.
You can purchase a bucketful of "beneficial nematodes" from many garden centers. These contain little critters like spined soldier bugs, assassin bugs, wheel bugs and ground beetles which destroy Popillia japonica grubs and eggs in the soil.
The spring tiphia wasp was imported from China to control Japanese beetles in the United States. The female wasp burrows into the soil and lays its eggs on top of Japanese beetle grubs. When the eggs hatch, the baby wasps eat the beetle grubs. Istocheta aldrichi, a tachinid fly, is another species that operates the same way. These look like houseflies, but unlike pesky houseflies they prefer to remain outdoors.
Plants
Certain plants are distasteful to Japanese beetles, and the beetles rarely cause damage to them. These include red and silver maple, magnolia, lilac, poplar, and most evergreens. They typically do not eat green or white ash, boxwood, or flowering dogwood. Plants that you may wish to avoid because they especially attract Japanese beetles include Norway and Japanese maple, hollyhock, gray birch, fruit trees, roses, and chestnut.
Sarah Goodwin-Nguyen - Goodwin-Nguyen is the author of Key West: A Comprehensive Guide to Florida's Southernmost City (Parkscape Press, 2008) as well as an ebook ...
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