Where Do Japanese Beetles Go At Night?

If you're a gardener, you're likely familiar with the scourge of Japanese beetles.

These pests can wreak havoc on your garden, and it's important to know how to identify and manage them in order to keep your plants and flowers healthy.

Published: March 6, 2023.

When Are Japanese Beetles Most Active?

Japanese beetles, like most insects, are active during the day and tend to rest at night. Also, they are more active during warm days - they emerge once temperatures reach 70-75°F (21-24°C), but they prefer much warmer 85-95°F (29-35°C).

During the night, they will typically seek out a sheltered spot to rest, such as in the leaves or branches of trees, shrubs, or other plants. They also often burrow into the soil a few inches or hide in crevices or other protected areas.

However, it's important to note that Japanese beetles are attracted to light and may be more active around outdoor lighting at night. This can be especially problematic if you have outdoor plants or flowers near lights, as the beetles may feed on them during the night.

Overall, Japanese beetles are primarily active during the day and tend to rest at night but may still be attracted to light sources in the evening.

If you're trying to manage a Japanese beetle infestation, it's important to be vigilant both during the day and at night to prevent further damage to your plants and flowers.

How To Identify Japanese Beetles Adults and Larvas

Japanese beetles are a type of pests that are easily recognizable by their shiny, metallic green bodies and copper-colored wings. Adults are about half an inch long and can be found on plants during the day, feeding on leaves, flowers, and fruit.

Their larvae, also known as grubs, are a creamy white color with a brown head and can be found in the soil beneath your lawn or in the garden.

Grubs feed on grass and plant roots, causing significant damage to turf and the garden in general. If you notice patches of brown or dead grass on your lawn or even dying or yellowing plants in the garden, it could be a sign of Japanese beetle infestation.

Lifecycle Of Japanese Beetles

Japanese beetles have a one-year lifecycle that begins in late June or early July when the females lay their eggs in the soil. The eggs hatch into grubs, which feed on the roots of turf until the fall.

Grubs then burrow deeper into the soil to overwinter. In the spring, the grubs return to the surface to feed on grass roots until they pupate and emerge as adults in late June or early July. The adults mate and lay eggs, beginning the new cycle.

Adult Japanese beetles tend to live for ~60 days, and generally, they die well before winter. In warmer areas, Japanese beetles may reproduce twice, while in colder areas, their lifecycle may last two years instead of one year.

Japanese Beetles Damage

Japanese beetles can cause significant damage to plants and turf. Adult beetles feed on the leaves, flowers, and fruit of plants, leaving them ragged and skeletonized.

Grubs can cause damage to turf by eating the roots, which can lead to dead patches of grass and damaged or even dead plants in the garden.

How To Manage Japanese Beetles

There are several methods for managing Japanese beetles. One option is to physically remove them from your plants by handpicking them off and dropping them into a bucket of soapy water. You can also use insecticides to control the adult beetles, but be sure to follow the instructions carefully to avoid harming beneficial insects.

For grub control, there are several products on the market that can be applied to the soil to kill the grubs. However, it's important to note that these products can also harm beneficial insects and should be used with caution.

Another option is to plant Japanese beetle-resistant plants in your garden. Some examples include yarrow, lavender, and coneflower. By planting these species, you can help deter Japanese beetles from your garden.

Japanese beetles can fly, but they are not good fliers. If You find them in your home, they are there either by accident, or they are looking for warmth and shelter. Anyway, Japanese beetles don't bite and they don't transmit diseases to humans or animals.

For more about this topic, feel free to check our How to Get Rid of Japanese Beetles article.

Few Final Words

Japanese beetles are an invasive species that can cause significant damage to your garden. By knowing how to identify them and using the proper methods for management, you can help protect your plants and turf from these destructive pests.

Various insecticides can be of great help, just be aware that insecticides don't know which insects are pests and what insects are beneficial for the garden.