Japanese Beetle – Definition & Detailed Explanation – Tree Diseases and Pests Glossary

What is a Japanese Beetle?

The Japanese beetle (Popillia japonica) is a destructive insect that is native to Japan. It was first discovered in the United States in 1916 and has since become a major pest in many parts of the country. Japanese beetles are known for their metallic green bodies and copper-colored wings, making them easily recognizable. These beetles are about half an inch long and have six legs, with white tufts of hair along the sides of their bodies.

How to identify Japanese Beetles on trees?

Japanese beetles feed on a wide variety of plants, including trees, shrubs, and flowers. They are most commonly found on trees such as roses, linden, birch, and maple. When identifying Japanese beetles on trees, look for the following signs:

1. Metallic green bodies with copper-colored wings
2. Clusters of beetles feeding on leaves and flowers
3. Skeletonized leaves with only the veins remaining
4. Damage to fruit and flowers, causing them to wither and die

What damage do Japanese Beetles cause to trees?

Japanese beetles can cause significant damage to trees by feeding on their leaves, flowers, and fruit. When Japanese beetles feed on tree leaves, they skeletonize them by eating the tissue between the veins. This can weaken the tree and make it more susceptible to disease and other pests. In addition, Japanese beetles can also damage fruit and flowers, causing them to wither and die prematurely.

How to prevent and control Japanese Beetles on trees?

There are several methods that can be used to prevent and control Japanese beetles on trees:

1. Handpick beetles: One of the most effective ways to control Japanese beetles is to handpick them off trees and plants. This can be done early in the morning when the beetles are less active.

2. Use traps: Japanese beetle traps can be effective in reducing beetle populations. These traps use pheromones to attract beetles, which then become trapped in a bag or container.

3. Neem oil: Neem oil is a natural insecticide that can be sprayed on trees to repel Japanese beetles. It works by disrupting the beetles’ feeding and reproductive cycles.

4. Plant resistant trees: Some trees, such as cedar, holly, and boxwood, are less attractive to Japanese beetles. Planting these trees in your yard can help reduce beetle damage.

What are natural predators of Japanese Beetles?

There are several natural predators of Japanese beetles that can help control their populations:

1. Birds: Birds such as starlings, robins, and grackles feed on Japanese beetles and their larvae. Providing bird feeders and bird baths in your yard can attract these natural predators.

2. Tachinid flies: Tachinid flies are parasitic insects that lay their eggs on Japanese beetles. The fly larvae then feed on the beetle, eventually killing it.

3. Predatory beetles: Some beetles, such as the ground beetle and the soldier beetle, feed on Japanese beetle larvae in the soil. Planting flowers that attract these predatory beetles can help control Japanese beetle populations.

How to treat trees affected by Japanese Beetles?

If your trees have been affected by Japanese beetles, there are several treatment options available:

1. Insecticidal soap: Insecticidal soap can be sprayed on trees to kill Japanese beetles on contact. Be sure to follow the manufacturer’s instructions for application.

2. Systemic insecticides: Systemic insecticides can be applied to the soil around trees, where they are absorbed by the roots and transported throughout the tree. This can provide long-lasting protection against Japanese beetles.

3. Prune affected branches: If Japanese beetles have caused significant damage to tree branches, prune them to promote new growth and reduce stress on the tree.

By following these tips, you can effectively prevent and control Japanese beetles on your trees and minimize the damage they cause.