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Japanese Beetles: “Send Me No Flowers—At Least, Not Geraniums!”

ARS entomologist Christopher Ranger observes healthy (left petri dish) and paralyzed (right petri dish) Japanese beetles after the beetles on the right consumed extracts isolated from geranium flowers.  ARS Photo.

ARS entomologist Christopher Ranger observes healthy (left petri dish) and paralyzed (right petri dish) Japanese beetles after the beetles on the right consumed extracts isolated from geranium flowers. ARS Photo.

This post is part of the Science Tuesday feature series on the U.S. Department of Agriculture blog. Check back each week as we showcase stories and news from the agency’s rich science and research portfolio.

Japanese beetles are tough hombres in the bug world, ripping and chomping their way through more than 300 plant species and nearly 80 plant families.  Farmers and ornamental plant growers spend more than $450 million annually on control measures and replacements for plants destroyed by the beetle, which is by far the most destructive pest of ornamental and turf plants in the eastern United States.

The beetle, Popillia japonica, is anything but a finicky eater. They’ll happily tear through a vast variety of plants, from corn and soybeans to fruits, vegetables and landscaping stock, to name but a few of their victims.

So delicate-looking geranium petals must look like colorful finger food to these ungainly flying marauders. Little do the beetles know that those petals pack a powerful wallop.

According to scientists with the Agricultural Research Service (ARS), the voracious beetles can’t resist chomping the geranium petals—but within half an hour of indulging their appetites, the beetles are flat on their backs, nearly paralyzed with only their legs and antennae twitching slightly.  It’s a classic case of “what goes around, comes around,” as the immobilized pests quickly become the prey of other hungry bugs.

In lab tests, the paralyzed beetles seem to fully recover within 24 hours, say the researchers at ARS’ Application Technology Research Unit in Wooster, Ohio.  But a day is more than enough time for other insects to find and devour the helpless beetles in the rough-and-tumble setting of farm fields.

Geranium flowers’ strange powers have been known since the 1920s.  But it’s only been in recent years that the ARS scientists have begun revisiting the potential of the petals.  Now they’re busy working on a natural, botanical formulation for controlling the beetles based on geraniums’ paralytic compounds, and say they’ll pursue a patent on their product.

2 Responses to “Japanese Beetles: “Send Me No Flowers—At Least, Not Geraniums!””

  1. Ivonne Vazquez says:

    Wonderful news! I always have potted geraniums (as well as the Japanese beetles) in my garden. Will make sure to increase the number of this plant, so thst I can spend less time picking off the beetles, which seem to prefer my raspberry plants above all else last summer.

  2. David L. Ford@pool filters and pumps says:

    Wow, this is great news. Now, there’s a natural way to kill (or paralyzed) those pest. Good job guys!

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