Japanese Beetle Battle
Protect your gardens and greenery from the relentless onslaught!
Protect your gardens and greenery from the relentless onslaught!
Growing along my front porch, a Virginia creeper rises up from the ground 10 feet below. It twists around a 6x6-inch porch support, and once reaching the railing, branches are trained left and right to provide the southfacing porch deck some protective shade during the summer.
Honestly, the plant isn’t very spectacular or showy. Once the leaves emerge from their buds in May, small, inconspicuous clusters of greenish flowers follow in June. These mature into dark blue, grape-like berries in late summer that last into fall and are relished by house wrens, robins and other birds that dare to light close to the house for an autumn feast.
Beyond that at the bottom of the hill is our vegetable garden. During the growing season, it’s filled with rows of green and yellow beans, beets, squash and other vegetables.
Surrounding the house itself are rock gardens filled with various flowers and shrubs, some purchased, but most gifted by friends and relatives. Built over the years, they are part of our rural utopia. We take pride in what we’ve built and work hard to maintain it, but it has been a battle.
The Battle Begins
When we purchased our property, built the house, moved in from town and started landscaping, we had no idea battling deer, woodchucks and other wildlife, as well as insects, would be part of the rural routine. Surprisingly, wildlife proves easier to deal with than various insects. One of the worst to cope with is the Japanese beetle, Popillia japonica.
Where They Came from and Where They Live
As their name implies, these iridescent, coppery/green-colored little buggers are natives of Japan. The first adults appeared on American soil in 1916 at a nursery in New Jersey, believed to have arrived as grubs in a shipment of iris bulbs a few years earlier. In Japan, the beetles cause little damage and are controlled by natural predators, but America was new territory, and with no natural defense measures, the beetles quickly moved west, north and south.
By 2002, two years after we moved into our new home and started landscaping and
enjoying the fruits of labors, Japanese beetles had become established in nearly every state east of the Mississippi. Today, they have firmly extended claim to areas in at least eight states in the Midwest and are pushing westward. According to the U.S. Department of Agriculture, Japanese beetles are now one of the most widespread and damaging pests of turf, landscape and ornamental plants in the United States as well as fruit, garden and field crops, with damages and losses estimated at more than $450 million annually.
What They Eat and How They Damage
As we quickly discovered, Japanese beetles don’t discriminate when it comes to eating. Over a few years, we toiled putting in everything from fruit trees and berry bushes to ornamental shrubs to perennial flower beds, not to mention a vegetable garden. Japanese beetles thanked us and took advantage of it all.
We didn’t know it at the time, but out of necessity and frustration, we learned from our local extension service that the pests are known to feast on some 300 different plant species. On their impressive menu are some of the most popular and desirable fruit trees, ornamental shrubs and flowers and garden crops.
In the adult stage, Japanese beetles are especially drawn to beans, grapes, peppers, tomatoes, raspberries, blueberries, blackberries, strawberries and apple, pear and peaches trees. The adults will also eat the fruits and berries of these plants. Much to my wife’s chagrin, roses are also a favorite target. In severe cases, the larva or grub will dine on the roots of these plants and many others. Chances are if you grow it, or if it grows naturally on your property, Japanese beetles will take advantage of it.
Typically, adult insects begin eating along the uppermost part of a plant in full
“Japanese beetles are now one of the most widespread and damaging pests of turf, landscape and ornamental plants in the United States … with damages and losses estimated at more than $450 million annually.”
sun, consuming the greenery downward between the veins, eventually turning the leaves into a brownish, lace-like skeleton. If left unattended, the entire plant becomes entirely or partially skeletonized, if not defoliated.
In the grub stage, along with ornamentals, certain shrubs and many garden plants and the roots of grass and sod are especially susceptible. As a result, the plant’s ability to take in water and nutrients is reduced, especially in hot, dry weather, eventually turning entire patches brown.
It took us a few years to realize some important things about Japanese beetles. One is that infestation is worse during some years than others. Mild winters with lessthan-average snow cover and soils that freeze more deeply followed by dry, warm springs seem to reduce grub and adult numbers.
Adult female beetles instinctively lay their eggs in areas with adequate moisture to ensure offspring survival. And while older grubs are more tolerant of deeper freezes and dry spring conditions, even traveling deeper into the soil if necessary, in general, beetles in the grub stage seem to proliferate in normal soil conditions, and can withstand high levels of soil moisture during wet springs. We’ve come to appreciate those rare mild winters and drier springs. But, we can’t always depend on Mother Nature to cooperate.
Another thing we’ve learned is both grubs and adult beetles cause damage, and controlling one life stage may not prevent damage from the other. In fact, it seldom does. Both must be dealt with separately, and because Japanese beetles utilize such a wide variety of plants (often in large numbers), completely eradicating them is virtually impossible. There are, however, ways to minimize the damage and fight back.
Preferring not to rely on chemicals unless absolutely necessary, our first attempts at battling adult beetles included attracting more birds to our property. Over time, several feeders, bird baths, a couple of small fountains and nesting boxes were placed, and we planted shrubs and ornamentals receptive to birds. Honestly, it’s difficult to say whether the additions have made an impact. I believe they do during years of low infestation when natural foods are less abundant, and during years of drought when birds flock to our water sources. But, they certainly haven’t hurt, and have added a level of aesthetic appeal to our property.
We discovered one helpful thing by mistake while dealing with deer and other wildlife invading our vegetable garden. During our second planting season, our beans were doing fine and were about ready to flower, but one morning while visiting the garden, we discovered the tops had been munched on overnight. The entire outer row looked like a freshly trimmed hedge. Before it got out of hand, we started using floating row covers, leaving them on each day until the crops matured, taking them off during the day and replacing them at night when flowering. It solved the deer problem, and even though adult beetles were still evident, the plants were mature enough to produce.
Light-weight row cover material is relatively inexpensive and easy to use, is readily available at garden-supply stores, and can be used on fruit trees, bramble bushes and even flowers. Further, it will not damage tender, young plants and will hinder sun scalding.
Another measure we’ve taken is to continually plant shrubs, trees and
“… both grubs and adult beetles cause damage, and contolling one life stage may not prevent damage from the other.”
(above) Soon after emerging in June, July and August, depending on location, adult Japanese beetles start mating. Eggs are deposited into the soil where they develop into grubs, emerging as adults the following year. (opposite) An adult Japanese...
(above) Row covers are an inexpensive method of reducing beetle damage. (below) During periods of low infestation, Japanese beetle traps can help control damage, but must be placed properly away from plants to be protected. Because Japanese beetles...
(above) Adult Japanese beetles mate on a lily. (below) Adult Japanese beetles will feed on more than 300 different plants, trees and shrubs, particularly grapes, one of their favorite targets. PHOTOS BY AL RAYCHARD