Japanese beetles are an invasive species. They were originally from Japan, but they came to the East Coast of the US in the early 1900s. Since then, they’ve been spreading slowly westward. They don’t enter homes in large numbers, but they’re a danger to yard plants and gardens.
What Japanese Beetles Look Like
You can recognize Japanese beetles by these features:
- Metallic Coloring: Their heads are a shiny metallic green, and their wing covers are copper-brown.
- Length: Each is about 1/3 to 1/2 an inch long.
- White Hairs: The sides of their bodies have two tufts of white hair near the front and five more near the back.
- Grubs: Their young are from 1/8 of an inch to one inch, shaped like the letter “C,” and have a tan head, white or cream bodies, and visible legs.
Damage Caused by Japanese Beetles
An infestation of Japanese beetles can do major damage to your garden, decorative plants, and/or crops. They eat about 300 different types of plants, including:
- Fruit trees, such as plum, cherry, and apple, among others
- Linden trees
- Rose bushes
- Crabapple trees
- Crape myrtle trees
- Birch trees
Every year, Japanese beetles destroy many crops in the Eastern and Midwestern United States. They “skeletonize” leaves, which means they eat all the tissue in a leaf except the veins, leaving only a skeleton behind. They also bite into fruits and flower buds.
Japanese beetle grubs eat the roots of grasses, killing them gradually and loosening soil. You might notice your grass turning off-color. As you water it, it may improve slightly for a time or not improve at all. Separate patches may die, and the soil may feel like a sponge when you walk on it. Finally, you may be able to pull up the loose turf by hand to see grubs crawling underneath.
Long-Term Effects on Plants
If you have healthy older trees, they can survive an attack by Japanese beetles. But if you have younger trees or other plants that were struggling to begin with, Japanese beetles can kill or permanently damage them.
A flowering plant like a rose bush won’t be completely killed by Japanese beetles, but they will often destroy their flower buds.
If you have a garden or an orchard, your herbs, vegetables, and fruits can survive a small amount of damage from Japanese beetles. But if the infestation continues too long, your plants may not be able to grow or produce as much food as you would like.
Signs of a Japanese Beetle Infestation
If you have Japanese beetles on your property, you’ll see these signs:
- Leaves that have been reduced to skeletons while still on the plant
- The presence of a single Japanese beetle, which often means there are others, because they send out a signal to attract other beetles while feeding
- Japanese beetle grubs burrowing in your soil
- Beetles on the ground under trees and bushes
- Brown patches of grass and/or loose turf
Tips for Getting Rid of Japanese Beetles
If you have rows of plants, you can protect them with row covers. This is often needed for about two months during the summer, starting in May or June, when Japanese beetles feed on plants. Be sure to let pollinators in, though, if you need them.
You can also pull the beetles off of your plants by hand, dropping each one into a bucket of water and dishwasher detergent, or you can shake them off onto a cloth on the ground.