How To Get Rid of Japanese Beetles

Japanese beetles (Popillia japonica) are considered harmful to gardens because they feed on the leaves, flowers, and fruit of a wide variety of plants.  To control Japanese beetle populations in a garden, there are a few methods that can be used.

What are Japanese Beetles?

Japanese beetles are a species of scarab beetle (Popillia japonica) that are native to Japan. They are approximately 1/2 inch long (1 cm) and 1/4 inch wide (0.5 cm), with a metallic green body and bronze wing covers. They have six legs, two antennae, and mandibles that they use to feed on plants.

Japanese beetles are considered a major pest in many parts of the world, including North America and Europe, where they are not native. They have a wide host range and can cause significant damage to crops, gardens, and landscapes by feeding on the leaves, flowers, and fruit of various plants. The larvae of the Japanese beetle, which are plump, white grubs, feed on the roots of grasses and other plants and can cause damage to lawns and turfgrass.

The Japanese beetle has a complete metamorphosis life cycle, which includes four stages: egg, larva, pupa, and adult. The life cycle typically takes one year to complete, although, in some areas, multiple generations may occur in a single season. Understanding the life cycle of the Japanese beetle is important for effective control and management, as different stages of the beetle can be targeted with different control methods.

How Much Damage Do Japanese Beetles Do?

Japanese beetles can cause significant damage to a wide variety of plants, including ornamental trees and shrubs, crops like beans, raspberries, and grapes, and lawns and turfgrass. Here are some ways in which Japanese beetles can damage plants:

1. Leaf damage: Adult Japanese beetles feed on the leaves of plants, leaving behind a characteristic skeletonized appearance with only the veins remaining. This can cause unsightly damage and reduce the overall health and growth of the plant.
2. Flower and fruit damage: Japanese beetles can also feed on the flowers and fruit of plants, causing damage to their appearance and reducing the yield of crops.
3. Grub damage: The larvae, or grubs, of Japanese beetles, feed on the roots of grasses and other plants, causing damage to lawns and turfgrass. This can result in patches of wilted or dead grass, as well as attracting other pests, such as skunks and raccoons that dig for food.
4. Defoliation: In severe infestations, Japanese beetles can cause complete defoliation of plants, leading to reduced growth, stress, and death.

It’s important to detect and control Japanese beetles early to prevent significant damage to plants. Implementing an integrated pest management (IPM) program that combines multiple control methods can be the most effective way to manage Japanese beetles and reduce plant damage.

5 Methods to Control and Get Rid of Japanese Beetles

1 – Get Rid of Japanese Beetles with Physical Control

Physical control is one method that can be used to get rid of Japanese beetles without the use of chemical insecticides. Here are some physical control methods for managing Japanese beetles:

1. Hand-picking: Hand-picking adult Japanese beetles off plants and dropping them into a bucket of soapy water can be an effective control method for small infestations.
2. Row covers: Installing row covers or netting over susceptible plants can prevent adult Japanese beetles from feeding on them. Be sure to secure the edges of the covers or netting to prevent beetles from getting inside.
3. Pheromone traps: Pheromone traps can be used to lure adult Japanese beetles away from plants. However, be aware that these traps can actually attract more beetles to your garden or landscape, so use them with caution.
4. Knockdown sprays: Using a water hose to knock adult Japanese beetles off plants and into a bucket of soapy water can be an effective control method. This can also help to reduce the population of beetles in the area.

It’s important to implement physical control methods in conjunction with other control methods, such as cultural control and biological control, for the most effective and sustainable control of Japanese beetles. Physical control methods can be especially useful for small infestations or for controlling Japanese beetles in small areas, such as potted plants.

2 – Get Rid of Japanese Beetles with Biological Control

Biological control is a method of using natural predators, parasites, and pathogens to control Japanese beetles. This method can be an effective and sustainable way to eliminate Japanese beetles without using chemical insecticides. Here are some biological control methods for managing Japanese beetles:

1. Natural predators: Birds, such as crows, blue jays, and grackles, feed on adult Japanese beetles and can help to reduce their populations. 
2. Parasites: Parasitic wasps, such as Tiphia vernalis, attack and lay eggs in adult Japanese beetles, killing them. The larvae of the wasps feed on the internal organs of the beetles and eventually pupate inside the beetle.
3. Pathogens: Certain pathogens, such as fungi and bacteria, can infect and kill Japanese beetles and their larvae. Beauveria bassiana is a type of fungus that is effective against Japanese beetles, as it infects and kills both the adults and the larvae.

Implementing biological control methods as part of an integrated pest management (IPM) program can help to reduce the population of Japanese beetles and minimize damage to plants. Additionally, because biological control methods are based on natural predators, parasites, and pathogens, they are often considered safer and more environmentally friendly alternatives to chemical insecticides.

3 – Get Rid of Japanese Beetles with Pheromone Traps

Pheromone traps are a method of controlling Japanese beetles by using a synthetic hormone called a pheromone to lure adult beetles into a trap. The pheromone mimics the scent produced by female Japanese beetles to attract male beetles, who are then trapped in the device.

While pheromone traps can be an effective way to monitor the presence of Japanese beetles in your landscape or garden, they can also attract more beetles to the area, so use them with caution. Here are some tips for using pheromone traps to get rid of Japanese beetles:

1. Location: Place pheromone traps away from plants you want to protect, and place them in areas where they will not attract more beetles to your garden.
2. Timing: Place pheromone traps in the early morning when the beetles are not yet active. This will help to prevent the traps from attracting additional beetles to your garden.
3. Maintenance: Check the traps regularly and dispose of the trapped beetles to prevent them from attracting other pests, such as wasps, to your garden.

4 – Get Rid of Japanese Beetles with Cultural Control

Cultural control is a method of controlling Japanese beetles by modifying the cultural practices in your landscape or garden to make it less attractive to pests. This method can be an effective and sustainable way to eliminate Japanese beetles without using chemical insecticides. Here are some cultural control methods for managing Japanese beetles:

1. Plant selection: Choose plants that are less attractive to Japanese beetles, such as plants that produce a strong odor or plants that are not preferred by pests. Some examples of plants that are less attractive to Japanese beetles include catnip, chives, garlic, nasturtium, or tansy.
2. Irrigation: Watering plants in the morning, rather than in the evening, can help to reduce the presence of Japanese beetles by keeping the foliage dry, which can make the plants less attractive to pests.
3. Timing of planting: Planting susceptible plants, such as roses and grapes, later in the season, after the adult beetles have emerged and started feeding, can help to reduce damage to the plants.
4. Clean-up: Removing and destroying any infested plant material, such as leaves or stems, can help to reduce the population of Japanese beetles in the area and prevent them from laying eggs in the soil.

By implementing cultural control methods, you can make your landscape or garden less attractive to Japanese beetles, which can help to reduce their populations and minimize damage to plants. Additionally, cultural control methods are often considered a safer and more environmentally friendly alternative to chemical insecticides. It’s important to monitor your landscape or garden regularly for signs of Japanese beetles and to implement a combination of control methods, including physical control, biological control, and chemical control, if necessary, to effectively manage the pests.