Garden Dilemmas, Delights & Discoveries, Ask Mary Stone, New Jersey Garden blog

Safely Controlling Japanese Beetles

a cluster of shiny green and rust colored Japanese Beetles feeing on a plant

Hello fellow readers,  In last week’s chat, we marveled over the miracle of a robin’s nest though we don’t feel the same about baby insects, other than perhaps caterpillars that turn into butterflies. We sure don’t feel the same way about Japanese beetles wreaking havoc in our gardens. There are ways of safely controlling Japanese beetles — some may not be for the queasy at heart, but they are sure to bring a laugh. (Hint- you may be more cautious about drinking a margarita :^)

a cluster of Japanese Beetles looking lifeless on rose buds

Pyrethrin, a safe way to control Japanese beetles, is working on contact.

Safe ways to control Japanese Beetles

Japanese beetles (Popillia japonica) spend most of their lives underground before emerging in June to feed and mate, then lay their eggs back in the soil in September. Their crescent-shaped grayish-white larvae are grubs that live in the ground and feed on the roots of grasses and plants. And so they can become a menace before they become good-looking beetles sporting a green and gold iridescent shell that chew the heck out of our plants.

We’ve shared remedies over the years, such as handpicking and throwing them in water. Then there’s organic insecticide such as Pyrethrin, derived from chrysanthemum flowers, that kills the suckers almost on contact. (Link to Japanese Beetle Time below for more information about Pyrethrin).

Yes, there are chemical pesticides and grub controls if you are inclined, but I’d rather you gather Japanese beetles as good old mom hired us to do at five cents per Jiffy jar full. Early morning is the best time as they are sluggish and will easily fall into your jar or bucket. You can drown them in soapy water or use plain water to feed them to your chickens or pond fish.

Or “cook the suckers,” as Mom would say as she tossed them into boiling water (out of character as she’s ordinarily compassionate about critters). But disrespectfully defoliating the garden changes things.

Long-term remedy for controlling Japanese beetles 
a green and rust colored Japanese Beetle on a green leaf

Japanese Beetle / Popillia japonica

You can markedly cut the population of Japanese beetles with a long-term remedy of Milky Spore—a biological control using milky disease spores. It’s a safe, all-natural bacteria lethal to grubs but harmless to humans, pets, and beneficial insects. Dispense about a teaspoon every 4 feet. Grubs ingest the spore, die then spread the bacteria into the soil that will live for 10-15 years.

I heard if your puree the bodies in a blender and add water to create a spray for plants they chomp, it will infect more grubs with the milky spore disease. Just don’t invite me for a margarita after :^).

How Japanese Beetles came to the US – It’s a Small World (After All). 

So how did they get here? Like many insect pests and invasive plants, they came by accident. Japanese beetles arrived in the rootstock of plants for the 1916 World’s Fair. They were first found in New Jersey in the same year and now are in every state in the eastern US except Florida. And the invasive critters continue to move west.

Speaking of World’s Fair, I vividly remember attending the one in New York in 1964 as a child *. The most memorable exhibit was a boat ride with an assortment of animated animals, plants, and people of different nationalities singing– It’s a Small World (After All). It was written by Richard and Robert Sherman, aka the Sherman Brothers, Walt Disney’s staff songwriters, during the aftermath of the 1962 Cuban Missile Crisis.

You likely know the lyrics which start with, “It’s a world of laughter, A world of tears, It’s a world of hopes, And a world of fears. There’s so much that we share. That it’s time, we’re aware. It’s a small world, after all.”

I’ll bet the chorus of It’s a Small World (After All) rings in your ears as you read the lyrics.

The song ends with, “There is just one moon, And one golden sun And a smile means, Friendship to everyone. Though the mountains divide, And the oceans are wide, It’s a small world after all.”

Why Japanese beetle traps backfire:

Back to beetle remedies. Japanese beetle traps can backfire. Studies have shown that pheromone lures attract far more to your garden than you’ll trap. By hanging one in your yard, you’re inviting the neighborhood of beetles to your garden. Sure, you’ll trap a bunch, but the rest will enjoy the call to dinner. Maybe a gift idea for your neighbor? Just kidding—It’s a small world, after all. And while it’s sad the world hasn’t changed much since the Sherman Brothers wrote the lyrics, we can help grow our small world into a bigger world of kindness and love. It starts at home and in our communities.

Garden Dilemmas? (and your favorite Podcast App.)

There’s more to this story in Episode 65 of the Garden Dilemmas Podcast:

* a personal reflection –  While waiting in line for the attraction, I held the hand of who I thought was my father. I looked up to find that it was another man’s hand, which became a point of laughter for my family. I felt exceedingly embarrassed. While I have no other memory of holding Dad’s hand as a child, I hold dear to my heart holding his arm on my wedding day and the sacred time I held his hand during his last days. Always hold your loved ones’ hands and keep them in your heart. A long-ago column about holding hands –Thanks for giving Thanks

Link to Japanese Beetle Time to learn more about Pyrethrin for controlling Japanese beetles.

Link to St. Gabriel Organics Milky Spore Powder and Bonide Japanese Beetle Killer with Pyrethrin

Link to It’s a Small World (After All) by The Sherman Brothers



Mary Stone, owner of Stone Associates Landscape Design & Consulting. As a Landscape Designer, I am grateful for the joy of helping others beautify their surroundings which often leads to sharing encouragement and life experiences. These relationships inspired my weekly column published in THE PRESS, 'Garden Dilemmas? Ask Mary', began in 2012. I dream of growing the evolving community of readers into an interactive forum to share encouragement and support in Garden and Personal Recoveries - seeking nature’s inspirations, stimulating growth, weeding undesirables, embracing the unexpected. Thank you for visiting! Mary
  1. Virginia Dipierro Reply

    I have a TV show called “Melodies and Memories”…I sing the song on the show, and when I do live shows I ask for a show of hands of anyone who ever rode on the boat and sang the song! I rode the ride both at the Worlds Fair and Disney World. And oh yes, now I have the beetles!! LOL

    • Mary Stone Reply

      Thanks for sharing, Virginia; I’ll certainly check out your show. It’s a small world, after all, :^) – too small to share with Japanese Beetles (smile). Thanks for reading my column, Mary

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