Japanese Beetles – Plant Destroyers

Japanese Beetles come from Northern Japan. They made their first appearance in the United States back in 1916, and populations of this pesky insect have been spreading West ever since. This beetle likes warm and humid weather, so Georgia property owners should be aware of their effect on lawns and gardens this summer. 

Japanese Beetles can be highly destructive if left uncontrolled. Japanese Beetle larvae (grubs) feed on roots of turfgrass destroying all kinds of landscapes surrounding homes and businesses—even pastures and farmland. Japanese Beetle adults feed on hundreds of types of foliage, flowers, and fruits.  

What are Japanese Beetles?

Japanese Beetles are small insects that feed voraciously on tender roots, grass and plant leaves. Aside from Northern Japan, Japanese Beetles can be found in many countries including China, Portugal, Russia and Canada. In the U.S., populations have been tracked in many states east of the Mississippi River, and about 30 states all together. Although these insects like warm, humid weather, they have not been able to establish themselves in Florida—the state with perhaps the most warm and humid climate. 

What do Japanese Beetles look like?

Japanese Beetles are about ½ inch long and have metallic, copper-colored wings that cover their shiny green back. It has six legs and two antennae on its bright green head. Japanese Beetles begin in the larvae stage and spend the first 10 months of their lives underground feeding on the roots of turfgrasses and plants. By late spring, they are fully adults and emerge from the ground and begin to feed on the leaves.  

What kind of damage do Japanese Beetles cause?

Japanese Beetles feed on the upper leaf surface of plants and grass chewing holes throughout the lush, green growth. Although the damage they cause is not deadly to the plant, their feeding pattern leaves behind a lacy appearance, which makes the plant look skeletal. These beetles can devour entire flower petals still leaving the plant alive and well without affecting the plant’s longevity.

There are about 300 plant varieties whose leaves Japanese Beetles enjoy feeding upon, including roses, marigolds, grapes, soybeans, basil, and hollyhock. They also enjoy the leaves of trees including cherry, apple, plum, birch and elm. 

Underground grubs can kill a lawn by feeding on the roots of turfgrass, weakening the roots to the point they can’t absorb much needed water and nutrients.

When Japanese Beetles attack, they will leave behind a skeleton of a plant. Unlike other pests that devour entire leaves, Japanese Beetles chew holes all throughout the leaf surface.

How can I prevent a Japanese Beetle Infestation?

When selecting plants for the garden, it’s best to choose plants that will deter Japanese Beetles from devouring them. Plants that repel them such as columbine, begonias, dogwoods, impatiens, hostas and lilacs. Also, incorporating fragrant plants into your landscape, such as garlic, can also deter Japanese Beetles from making a home in your yard. 

The healthier your lawn is, the less likely Japanese Beetles can kill it. Water and fertilize according to the type of turfgrass you are growing, and maintain the correct mowing height. If you suspect Japanese Beetles are in your grass, it’s a good idea to cover garden plants with netting (cheesecloth) and covers that will stop them from getting onto the leaves. Cheesecloth still allows moisture and sunlight in, while keeping bugs out.

How can I control these pests?

Organic methods are best for controlling populations of Japanese Beetles. Handpicking adult beetles from plants and placing them in a bowl of water with a little dish soap in it will stop them from being able to lay eggs and further infest your landscape. 

Homemade remedies such as spraying down plants and grasses with soapy water or natural insecticidal oils can deter them from making a meal out of your greenery. 

Nematodes, including Steinernema glaseri and Heterorhabditis bacteriophora are the two most effective at attacking Japanese Beetle larvae and pupa.

What chemical control options are best?

Controlling populations of Japanese Beetles chemically is challenging because chemical options could kill off healthy organisms and create potentially harmful runoff. Natural predators of Japanese Beetles include birds, spiders, and stink bugs.

Low-risk insecticides, such as pyrethrins, can be effective, but it takes diligence and many applications. However, they are toxic to bees and other beneficial insects.

Neem oil is a lower risk to bees and other beneficial bugs and bacteria, but its effect only lasts for several days and must be reapplied.  

Bacillus thuringiensis galleriae comes from soil bacteria and is one of the most effective at controlling adult populations of Japanese Beetles for up to two weeks. 

If choosing a chemical treatment, contact Simply Green for the most effective and safest chemical applications. 

How do I know which method to use?

Practicing the Integrated Pest Management (IPM) Approach to pest control can help you determine which method(s) to put in place. Before any treatment is done, a series of evaluations take place to gauge the seriousness of the problem and the best solution is considered. 

Ideally, the IPM approach begins before the first seed of grass or new plants go into your yard to foster a pest-resistant landscape. Monitoring and regular maintenance creates long-term success.

Simply Green Lawn Care Plus can help!

Simply Green experts educate homeowners on the importance of proactive pest management and the environmental significance of organic and sustainable pest control. Remember to check leaves often for signs of pesky invaders, such as Japanese Beetles, that can ruin your garden. Incorporate predatory bugs that wi

ll feed on pests, and not your plants. Research and choose plant varieties that will resist a Japanese Beetle infestation. Healthy plants are more resistant to pests. The key to a thriving lawn and garden is balancing your garden’s ecosystem to promote plant health. Adequate water, sunlight and nutrients promote strong plant growth, and proper pruning and spacing prevent overcrowding, which helps reduce the risk of pests and disease. Don’t know where to start? Need help? Contact Simply Green today!