The Saga of the Japanese Beetle in North America

Japanese beetle on button bush

Dogbane beetle, not to be mistaken by the Japanese beetle

You must admit that the Japanese beetle is a handsome insect. With iridescent coppery red wing covers and emerald green pronotum (the segment behind the head), it catches your eye. In fact, sometimes people mistake it for another little beauty, the dogbane beetle. The latter is a native one that feeds on dogbane and causes no trouble. The Japanese beetle is no problem in its native land, East Asia and Japan. But here, in North America, it is another story: it has been a headache for gardeners and farmers since its arrival in New Jersey around a century ago.

It most likely arrived in the root ball of some iris plants imported from Japan around 1911. It was first noticed a few years later, in 1916, in a nursery in New Jersey. In a couple of years, entomologists knew that they were facing a species new to the United States, and had tracked it down to its country of origin, Japan. It didn’t take long to realize the potential harm this beetle could do to crops and ornamentals and the war against the Japanese beetle began.

On common milkweed

The control methods used in those pre-Rachel-Carson days read like a horror story. The earlier pesticides included arsenate of lead and sodium cyanide. Of course, these pesticides killed a lot more than the intended target. These methods did not prevent the spread of the beetle. Pest tracking maps show growing circles radiating from its place of arrival in New Jersey, like those caused by a pebble dropped in a pond. The hope of eradication was abandoned, and the goal became containment. Quarantines were enforced, but nothing seemed to stop the advance.

On goldenrod

By the forties, a new pesticide, DDT, had emerged that was considered far more effective and less harmful than previous ones. At least that was the thought at the time. DDT did little to stop the advance of Japanese beetles. They were spreading farther and farther along the East Coast. But the Midwest and the West Coast were still safe.

Nowadays, there are gentler methods to control the Japanese beetle, biological controls such as parasitoids and pathogens. These are the ones that keep the beetle from becoming a pest in its native lands: parasitic wasps, called Typhia, nematodes and several bacteria. I am happy to report that a native wasp, the blue-winged wasp (Scolia dubia) has also become an enemy of Japanese beetles.

I am not trying to give advice on Japanese beetle control. There are several fact sheets easy to find in the Internet. But I find this detail delightful: Japanese beetle larvae like well mowed, watered and fertilized lawns. So, if you reduce the size of your lawn and keep it overgrown and somewhat thirsty and hungry, you are practicing Japanese beetle control. Tell that to your neighbors!

Map of Japanese beetle distribution. National Agricultural Pest Information System (NAPIS). Purdue University. “Survey Status of Japanese Beetle – Popillia japonica. Purple: present. yellow: found. Brown: being eradicated. Green: absent

How did this non-native species become so widespread in a century? Looking at the Pest Tracker map, we see that it is present in all the Eastern US (purple) and absent in most of the West (green). Residents of Midwestern and Western states may breathe easier, maybe. It is very significant that here and there, all the way to California, there are yellow and brown spots that indicate that the beetle has been found or is being eradicated, respectively. So, the question is: how did the Japanese beetle manage to jump those huge expanses of beetle-free land? It is not a strong flier; it can travel as far as five miles, but usually doesn’t go that far. Left to its own devices, it would be reaching Ohio and North Carolina, at most.

Japanese beetle on mallow

The Japanese beetle has other means of transportation; that means us. We constantly move plants, produce or cut flowers cross country; the beetles hunker down on them or their root balls and go for the ride to explore new lands. A Kansas gardener describes a recent experience at a nursery in a blog, “Japanese beetles for sale? Really?“. To his dismay, he found rose bushes for sale infected with Japanese beetles. The owners knew about it, the authorities knew about it; but not much was done. Most of the state is or was fairly clean from this pest; but not for long, it seems.

We can draw a few conclusions from the saga of the Japanese beetle in North America:
1. Introduced plants create problems, not just by becoming invasive, but by carrying pests, which in turn become invasive. It seems that most insect pests are introduced and further spread via live plants.
2. The battle against introduced pests is not always a battle to preserve native plants. The war against the Japanese beetle has been aimed primarily to non-native farm crops and ornamentals.
3. In the long run, pesticides are not effective. Other, more natural methods work better.

Photos by Beatriz Moisset. Map by National Agricultural Pest Information System (NAPIS)

Beatriz Moisset lives in Southeastern Pennsylvania, studies pollinators and gives presentations at nature centers, garden clubs. Guide to Flower Visitors

© 2012, Beatriz Moisset. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us

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About Beatriz Moisset

Born in Argentina and a resident of the United States for about forty years. A biologist by profession and a photographer and painter by avocation. I finally found the way to combine all these different interests in one single package when I became interested in pollinators. I have been photographing and painting them and studying their biology and ecology and I probably could spend the rest of my life doing so because the subject is endlessly fascinating and of tremendous esthetic, ecological and economic importance. Author, with Steven Buchman, of Bee Basics: An Introduction to Native Bees

Comments

  1. Donna@ Gardens Eye View says:

    Beatriz I was also going to mention these bug thugs along with another that is on its way to even more destruction in NY (emerald ash borer)in a couple of weeks. With the hot weather and drought these pests were even worse this year in the garden. We continue to reduce our lawn and we don’t fertilize or water it, but I find the grubs all over the garden. They are particularly destructive on my mallow even though we put up the new safe traps. They breed so much and so fast it is hard to control them, but we at least have fewer. I’ll check out the links in hopes of finding other safe methods of control.

    People who knowingly sell these beetle laden plants should be heavily fined or shut down. But it is still only about the money. Sad.
    Donna@ Gardens Eye View recently posted..Gardens Eye Journal-August 2012

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    • Donna@ Gardens Eye View says:

      Forgot to mention that I will link to and reference this great post as I do my post!
      Donna@ Gardens Eye View recently posted..Gardens Eye Journal-August 2012

      Reply
  2. Carole Sevilla Brown says:

    Beatriz, the benefits of lawn reduction are many, but I hope that we can spread the word that one of the best reasons to do this is to prevent more spread of Japanese Beetles! I think a lot of folks could get on board with that idea.
    Carole Sevilla Brown recently posted..The 5 Pillars of Ecosystem Gardening

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  3. Debbie says:

    Beatriz, Hooray for another reason to reduce the size of our lawns. Fortunately, Japanese beetles are not a big issue in my garden. Over the years I’ve removed several plants from my garden that were Japanese beetle magnets and try to hand pick any others I find. After reading your post I think my unknown silver bullet may be the fact that our lawn has slowly been shrinking in size and there is no supplemental irrigation and minimal fertilizing. It’s nice to see my hands-off gardening style may have hidden benefits.
    Debbie recently posted..Book Preview ~ Organic Gardening (Not Just) in the Northeast

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  4. Rambling Woods says:

    This is so interesting and the past 2 years I have not watered our lawn at all, not that I watered it much to begin with but I haven’t seen any japanese beetles on any of my plants this season and last where I used to see many…Another reason not to water the lawn..but my neighbors refuse to listen to any kind of reason in their lust for the green lawn..thank you for this post..I will try again..Michelle
    Rambling Woods recently posted..Nature Notes (#170)~I believe a leaf of grass is no less than the journey-work of the stars.~Walt Whitman

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  5. Ellen Sousa says:

    Very interesting about the blue-winged native wasp who parasitizes the Japanese beetle grubs! Evolution in action and yet another reason to avoid pesticides and watch how nature adapts…
    Ellen Sousa recently posted..Japanese Beetles, Chickens and the Habitat Farm

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  1. The Invasions Continue says:

    [...] This is the saga of the Japanese beetle.  And where did this beetle come from?  Well in all likelihood it was imported with plants over 100 years ago from Japan.  One hundred years and we still have this pest wreaking havoc. [...]

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  2. You Calling Me a Purist? says:

    [...] are less likely than plants from other lands to be the source of disruptive pests and [...]

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