Japanese Beetles on Crepe Myrtle: Effects and Best Solutions

Gardeners often praise crepe myrtles for their vibrant flowers and long-lasting beauty. However, they may occasionally face unwanted pests, such as the Japanese beetle.

Do crepe myrtles attract Japanese beetles? Yes, crepe myrtles can attract Japanese beetles. These beetles are generalists and feed on a wide variety of plants, and crepe myrtles are among their favorites due to their lush foliage and attractive flowers.

In the following sections, we’ll explore the world of Japanese beetles, helping you understand their identification, life cycle, seasonal activity, and the damage they cause.

You’ll also learn about their impact on crepe myrtles and strategies for managing them. 

Key Takeaways

  • Japanese beetles can cause significant damage to crepe myrtles, including leaf and flower damage, reduced growth, and increased susceptibility to other pests and diseases.
  • The life cycle of Japanese beetles includes four stages: egg, larva, pupa, and adult.
  • Management strategies include handpicking, trapping, use of insecticides, neem oil, natural predators and parasites, and homemade sprays.
  • While Japanese beetles can cause significant damage, they are rarely fatal to healthy, mature trees.

If you want to learn more, my article, Crepe Myrtle Diseases and Pests, has all the information you need for a variety of issues.

Understanding Japanese Beetles

Japanese beetles are a common pest in many gardens, feeding on a wide variety of plants and causing significant damage.

How To Identify Japanese Beetles

Japanese beetles are easily identifiable by their metallic blue-green bodies with copper-colored wings. They are about 1/2 inch long and have a pair of white tufts of hair on each side of their abdomen.

Japanese Beetle Life Cycle

The life cycle of a Japanese beetle consists of four stages: egg, larva, pupa, and adult. The females lay their eggs in the soil, which hatch into white grubs.

These grubs feed on the roots of grasses and other plants before pupating and emerging as adults.

Seasonal Patterns of Japanese Beetle Activity

Japanese beetles are most active during the warm summer months. The adults emerge from the ground in early summer and begin feeding and mating.

By late summer, the females start laying eggs in the soil, and the cycle begins anew.

Damage Caused by Japanese Beetles

Japanese beetles are voracious feeders and can cause significant damage to plants. They feed on the leaves and flowers, often leaving behind a skeletonized pattern.

In severe cases, they can defoliate a plant completely.

Prognosis of Affected Trees and Plants

While Japanese beetles can cause significant damage, they are rarely fatal to healthy, mature plants. However, a severe infestation can weaken a plant and make it more susceptible to other pests and diseases.

A single Japanese beetle on a completely skeletonized leaf.

Impact of Japanese Beetles on Crepe Myrtle Trees

Japanese beetles can have a significant impact on crepe myrtles, affecting their health, growth, and flowering.

Damage Caused

Japanese beetles feed on the leaves and flowers of crepe myrtles, often leaving behind a skeletonized pattern. In severe cases, complete defoliation can occur.

Without plenty of healthy leaves, the tree is unable to photosynthesize properly, and overall weakness results.

Effects on Tree Health, Growth and Flowering

The feeding damage caused by Japanese beetles can affect the overall health and growth of a crepe myrtle. The loss of leaves can reduce the tree’s ability to photosynthesize, leading to reduced growth.

Additionally, feeding on the flowers can affect the tree’s flowering and aesthetic appeal.

Secondary Issues

In addition to the direct damage, Japanese beetles can also lead to secondary issues. The feeding damage can make the tree more susceptible to other pests and diseases.

Also, the presence of Japanese beetles can attract birds that may cause additional damage while feeding on the beetles.

How To Get Rid of Japanese Beetles on Crepe Myrtles

Managing Japanese beetles can involve physical removal, trapping, use of insecticides, and introduction of natural predators. In many cases, a combined approach is best.

Handpicking Japanese Beetles

Handpicking is a simple and effective method for controlling small populations of Japanese beetles. This involves physically removing the beetles from the plant and dropping them into a bucket of soapy water.

Trapping Japanese Beetles

Traps like these can be used to catch and kill large numbers of Japanese beetles. However, they should be placed away from the plants you’re trying to protect, as they can attract more beetles to the area.

Spectracide Bag-A-Bug Japanese Beetle Trap


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Insecticides

Insecticides can be used to control Japanese beetles. It’s important to choose a product labeled for use against Japanese beetles, such as this one, and to apply it according to the manufacturer’s instructions.

3-in-1 Insect, Disease, and Mite Control for Plants, 32 Ounce


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Neem Oil

Neem oil is a natural pesticide that can be used to control Japanese beetles. It works by disrupting the insects’ feeding and growth. I use this organic neem and always see good results.

Natria Neem Oil Spray for Plants, 24-Ounce


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Introduction of Natural Predators and Parasites

Introducing natural predators, such as birds and certain types of wasps, can help control Japanese beetle populations. Parasitic nematodes can also be introduced into the soil to control the grub stage of the beetles.

Homemade Sprays

Homemade sprays, such as those made from soapy water or hot pepper, can be used to deter Japanese beetles. However, these sprays need to be reapplied regularly and may not be as effective as other methods.

Related Questions: 

What Deters Japanese Beetles?

Certain plants, such as garlic and rue, are known to deter Japanese beetles. Additionally, maintaining the overall health of your plants and trees and promptly addressing any beetle infestations can help deter these pests.

Can Japanese Beetles Kill a Tree?

While Japanese beetles can cause significant damage, they are rarely fatal to healthy, mature trees. However, a severe infestation can weaken a tree and make it more susceptible to other pests and diseases.

Closing Thoughts 

Japanese beetles can pose a significant threat to the beauty and health of your crepe myrtle. However, with regular monitoring, proper cultural practices, and the judicious use of insecticides, you can effectively manage these pests.

Remember that a healthy tree is the best defense against any pest or disease. With the right knowledge and tools, you can ensure that your crepe myrtle continues to be a stunning addition to your landscape.

Crepe Myrtle trees are often the target of pests and diseases. Here are some other concerns to be mindful of: