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When is Japanese Beetle Season?

Hungry pests can quickly cause problems in your garden. One bug that knows how to drive you and your plants crazy is the Japanese beetle. These pests have a habit of snacking on a variety of plants in large numbers, and they can cause significant damage to plants in the middle of summer. We’ve gathered information about Japanese beetles to help you identify and control these pesky insects.

What Are Japanese Beetles?

Japanese beetle on leaf

Japanese beetles are an invasive beetle species. The adults range in size from 1/3"-1/2" in length. These beetles have copper wings and a metallic green head. Patches of white hair can be found on their abdomen. Their larvae, also known as grubs, have a white body and tan head. Their c-shaped body can grow up to 1" in length.

When is Japanese Beetle Season?

These beetles make their arrival in late June and remain active into August. During this time, these pests reach their peak population and activity levels. Adult Japanese beetles live up to two months. The larvae hide deep in soil during winter. As temperatures warm in spring, they move upward toward the surface of the ground. After they develop into adults, they emerge in summer. These beetles are usually more active on warm, sunny days and prefer plants that are in direct sunlight.

Are Japanese Beetles Harmful to Plants?

Japanese beetle eating leaf

These pests can be harmful to plants. They feed on many plants including produce, trees, shrubs, and flowers. They are particularly fond of roses and flowering fruit trees. Their feeding can cause damage to leaves and flowers. If they feed on young or unhealthy plants, it can hinder plant growth or kill the plants. Japanese beetle larvae can also cause damage to grass. Damage from these pests can be significant since they feed in groups.

Where Can Japanese Beetles Be Found?

Japanese beetle infestations are most commonly found in all states east of the Mississippi River (except for Florida and Louisiana). However, Japanese beetles have started moving further west, and infestations have been reported in several states just west of the Mississippi River and Colorado.

Japanese Beetle Activity Map infographic

Signs You Have Japanese Beetles

Catching an infestation early can help prevent serious damage to your garden. Check out a few signs that these pests have found your plants.  

  • Spotting Beetles: The most obvious way to identify an infestation is seeing these pests. Adult Japanese beetles can be found on plants and flying around your garden. Grubs live in the soil and can be harder to detect.
  • Plant Damage: When these pests feed on plants they cause physical damage to leaves. Chewed leaves will look skeletonized. Some leaves may turn brown.
  • Grass Damage: Japanese beetle larvae feed on roots of grass. Their feeding can cause patches of brown or dead grass.

How to Get Rid of Japanese Beetles

Maggie's Farm Garden Essentials Beetle & Boxelder Bug Killer

When Japanese beetles invade your garden and landscape, you’ll want to act quickly. When dealing with just a few beetles, you can try picking them off your plants. However, these pests often attack in large numbers. Spraying your plants with a pyrethrin-based insecticide spray can help to get rid of them. Our Maggie’s Farm Beetle & Boxelder Bug Killer kills these pests on contact. Japanese beetles die shortly after being sprayed and often die while still on the plant. Our Beetle & Boxelder Bug Killer can be used on indoor and outdoor plants. While our 3-in-1 Garden Spray is great for other garden pests, it shouldn’t be used on Japanese beetles or if significant Japanese beetle populations are present in the area. These beetles may actually be attracted to any plant oil-based pesticide.  

No one wants to deal with hungry bugs attacking their plants. To protect your garden, you need to be diligent during Japanese beetle season. Identifying an infestation early and acting quickly can keep your plants safe from these pests. If you’re dealing with a bug problem, we have your back! Check out our Maggie’s Farm Pest Control products.

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