Japanese Beetles, like “the man who came to dinner,” stay too long and eat too much.
They are the world’s greatest freeloaders for four to six weeks during the peak of the summer growing season.
Since they were discovered near Riverton, New Jersey, in 1916, their range has gradually widened to include most of the eastern seaboard from southern Maine to North Carolina.
They are found westward into Ohio and West Virginia. Colonies have also settled in various states up to and beyond the Mississippi River.
Beetle’s Menu
In the United States, the Japanese beetle, Popilliae japonica, causes more damage than in Japan.
Ten months of the year or so they are underground as white grubs, feeding on roots and plant stems.
After going through a pupal stage they emerge in early summer as hungry, half-inch, shiny, metallic green adults with brown wings.
There are approximately 275 different plants on the beetle’s menu. However, there are also plants they eat sparingly or not at all.
Favorites of Japanese Beetles
These, of course, are the preferred ones if you are planning a new garden. Corn is one of the gourmet items of Japanese beetles.
They mass on the silk during the five- to seven day silking period and reduce the yield by preventing proper pollination.
Blueberries, grapes, raspberries, apples, cherries and peaches are other beetle favorites—particularly specimens that have ripened prematurely or are diseased.
The beetles’ favorites among ornamentals are the rose, shrub-althea, Virginia creeper, canna, dahlia, hollyhock, zinnia, marigold, marshmallow, and rose mallow—all of Oriental origin.
Shade Trees
Among the shade trees that rank high on their menu are horse-chestnut, larch, linden, Lombardy poplar, maple, oak, and willow.
The beetles chew out the tissue between the veins of the leaf. Some natural enemies have been imported to help stem the beetle tide.
The spring this from Korea and the fall Sophia from Japan are wasp-like parasites that prey on beetle grubs.
Natural Control For Japanese Beetles
These predators have become well-established in certain New Jersey localities. Another natural control is the milky disease.
It is harmless to humans, children, pets, beneficial insects, and plants but deadly to Japanese beetle grubs.
The Department of Agriculture has licensed several companies to manufacture and sell the dried, dormant disease organism. It is usually applied to lawn areas.
Among the birds that do their part in lowering the beetle population are starlings, English sparrows, gulls, and domestic poultry.
Dry summer weather helps by killing newly hatched grubs and destroying many eggs.
Spraying Operation
Collecting and trapping also provide temporary relief, but the most permanent control is using dust or sprays promptly and thoroughly. The manufacturer’s directions for mixing and applying should always be followed closely.
DDT will kill many beetles during the spraying operation and those that come in contact with the plant while the residue is still lethal.
It should not be used on berries or vegetables after forming the edible part. Do not use it on fruits later than thirty to forty days before harvesting.
Prevention of Re-Infestation
Methoxychlor is slower than DDT and is not as effective in preventing re-infestation, but it is less poisonous to animals and humans.
In addition, it may be applied closer to the harvest time of fruit—seven to twenty-one days, depending on the crop.
Malathion is one of the safest insecticides to handle and an excellent beetle killer. It can be applied as close as three to seven days before harvest time.
However, its effectiveness disappears after seven to ten days, so it must be applied quite frequently.
Valuable Rotenone
Rotenone is valuable for discouraging beetles from ripening apples, cherries, grapes, peaches, plums, raspberries, and ornamentals. It can be used within a day of harvest time.
Sevin is a new material that has proved outstanding against Japanese beetles in field tests.
Lawns may be protected for several years by one top aldrin, heptachlor, or dieldrin dressing.
Similarly effective are chlordane, DDT, and toxaphene—all applied according to manufacturers’ directions.
44659 by Peter Wyckoff