Naturally Repel Japanese Beetles While Tending To Your Garden

BY ALISSA SILBER

While it is calming to stop and smell the roses, it is not always pleasant to do so with Japanese beetles munching on your beautifully flowering plants. These metallic green-and-brown colored beetles mean no harm to humans but can cause damage to roughly 300 plant species.

Some of their favorite delicacies are roses, fruit trees, beans, corn, tomatoes, and ornamental shrubs and plants, according to The Connecticut Agricultural Experiment Station.

The United States Department of Agriculture’s National Invasive Species Information Center classifies Japanese beetles (scientifically called Popillia japonica Newman) as a terrestrial invasive species. They believe the insect was introduced to the United States around 1911 from Japan.

The center describes the Japanese beetle’s impact as a “Destructive pest of turf, landscape plants, and crops; adults feed on the foliage and fruits of several hundred species of trees, shrubs, vines, and crops, while larvae feed on the roots of grasses and other plants.”

As adults, they chew out the tissue between the veins of a leaf and leave intricate designs – similar to doily patterns.

Protect Our Pollinators (POP) Treasurer Mary Wilson has found from her research from University of Minnesota Extension that “adult Japanese beetle damage usually affects only the appearance of plants.”

According to the university, “Healthy, mature trees and shrubs can tolerate a lot of feeding without significant, long-term injury; Young or unhealthy plants may be stunted, injured, or even killed from severe, persistent feeding; Healthy flowering plants such as roses can survive Japanese beetle feeding. But the blossoms are often ruined by the insects; Fruits, vegetables, and herbs can tolerate limited leaf feeding, but severe damage may affect plant growth and reduce yield.”

So, while a few Japanese beetles are a nuisance, they are not always detrimental to gardens.

Organic Methods

While some people opt to apply harmful chemicals to eliminate Japanese beetles, Wilson advocates for using natural alternatives.

“POP is very opposed to the use of neonicotinoids which are commonly spread on lawns to kill grubs

(whether needed or not),” she said.

In a document from Wilson titled Alternatives for Neonicotinoids for Grub Control, it stated, “Neonics are to be avoided not only for their effect on pollinators but also for their effect on beneficial insects, birds, mammals, and aquatic life if they enter a water course, which is quite likely due to their solubility … The use of pesticides frequently is counter-productive resulting in the loss of beneficial insects, chemical dependency, depletion of soil bacteria, risk to other species, and possible pollution of water resources.”

Wilson finds that the best way to deal with Japanese beetles is to reduce/eliminate them in the grub stage of their lifecycle. To do so, she recommends homeowners spread a product called grubGONE! in their garden.

Its companion beetleGONE! is also effective and available online as well as at garden stores.

“beetleGONE! is a product a homeowner can use if they have beetles currently on roses or their vegetables, because it is safe for humans. It has been certified organic for organic farmers,” Wilson said.

The products promote that they are not harmful to pollinators, such as bees, butterflies, and lady bugs.

“Another way to prevent them is to have a lawn that is healthy and thick. Keep mowing your lawn at two inches or more and aerate it… what that does is shade out any place in the blades of grass, so you don’t get weeds or insects in there,” she said.

A temporary, but hands-on approach, that can also be done is picking the Japanese beetles off the plant and relocating them.

Wilson said, “Once they are on plants, removing them physically works as long as they are low enough to be reached. Also, a stream of water will send them flying off.”

Wilson says that while she does not have plantings in her home garden that attract many Japanese beetles, she has seen them in Newtown. She has spotted them enjoying the trees at Tammy’s Garden, located in the Newtown Municipal Center courtyard.

Since the Japanese beetles are posing no real harm to the trees at Tammy’s Garden, besides some holes in the leaves, they are leaving them to coexist peacefully with nature.

Reporter Alissa Silber can be reached at alissa@thebee.com.