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  • Writer's pictureLVHG

Fighting Japanese Beetles


Japanese beetles are half-inch long insects that belong to the scarab beetle family. You’ll notice them by their iridescent shells, which are copper-toned over the wings and metallic green everywhere else. The sides of the shells are dotted with tiny white hairs. These shells aren’t just interesting to look at—they’re tough as nails. This is one of the primary issues with Japanese beetle control: their tough shells make them resistant to most of the pest control products on the market for home use. Here’s some more bad news: Japanese beetles are big eaters. They will happily munch on, and destroy, any plant tissue they feel like eating. They arrived in the United States by mistake via air travel just a few decades ago, and therefore have no natural predators here. That means they’ve been free and able to reproduce and grow their populations every year.


Japanese beetles begin their reign of terror at the beginning of their life cycles. Adults lay their eggs in patches of grass, and the eggs hatch into grubs. From October until March, the grubs are lurking deep in the soil, waiting for things to warm up so they can travel to the soil surface and begin feasting on plant roots. By April, they’ll start attacking the roots, and by June they’ll reach maturity, emerging from the ground as adults, and leaving a dead brown lawn in their wake. Soon, they’ll begin mating, and the females will return to the soil to lay their eggs, to start the cycle all over again.

As adults, the beetles fly in packs and attack just about any plant that catches their eye, all summer long until mid-September. Their telltale damage leaves a lacy pattern on your leaves as they chew up the plant tissue between the foliage veins.

To make matters worse, the grubs are a food source for local wildlife, who can smell them just below the soil. Some of the Japanese beetle damage you might notice is indirect, caused by wild animals tearing up your sod and garden beds to hunt for grubs.


With their nearly indestructible shells, the best time to kill Japanese beetles is when they’re still grubs. That being said, it’s not impossible to kill the mature beetles, and we carry several products to help control these “pains in the grass.”

Scott’s® GrubEx® is a long-term grub killer that you apply once for four-month protection. The formula can be sprayed onto the grass directly from late spring to early summer, where it immediately attacks Japanese beetle larvae and other nasty grubs. We also carry Bayer Grub Control and GardenTech® Sevin®, which are available as spray formulas or lawn granules.

Some other great spray insecticide options we carry are Eight Insect Control: Yard & Garden, which is proven safe for use on vegetable gardens, and our Bioadvanced 3-in-1 Insect, Disease and Mite Control, which is specially formulated for trees, roses and flowers. Since Japanese beetles can fly, we recommend re-applying these sprays every couple of days until the bugs go away.

Another option available at our garden center in Allentown is St. Gabriel Milky Spore. Milky Spore is a beneficial fungus that affects Japanese beetle grubs and kills large populations of beetles before they emerge. This is a long-term solution, as concentrations of Milky Spore need to be built up over several years before the protection performs optimally. A combination of grub killers and Milky Spore treatments is your best plan of attack to control Japanese beetles populations, starting today.

If you’re not big on using chemical insecticides, or you’d like an effective backup method for getting rid of mature beetles, you can try a Beetle Bagger. This Japanese beetle trap uses a combination of floral aromas and insect pheromones to lure in the bugs, effectively trapping them in the disposable bag insert.

Japanese beetles put up a tough fight, but it’s a war that can be won. If you’re in the Allentown area, stop by our garden center for more advice on controlling these destructive pests.


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