Invasive insect
Japanese beetle
Popillia japonica
Japanese beetle identification: a metallic green beetle with coppery wing covers and five white tufts on each side. Its grubs feed on lawn roots.
Published Last reviewed
A Japanese beetle is a half-inch beetle with a metallic green body, coppery-brown wing covers and five small patches of white hair along each side of the abdomen. Those white tufts are the fastest check. Published sizes vary a little between extension services, from about 3/8 to 1/2 inch, so use the color and the tufts rather than the ruler.
The insect is really two problems on one page. The adult is the one stripping your roses, grapes and lindens in July, chewing the soft tissue between veins until the leaf looks like lace. The grub is the white, C-shaped larva in the lawn, feeding on grass roots from late summer into fall. Heavy feeding can kill turf in patches, especially in a dry year, and the damage often shows up as loose, spongy grass that peels back from the soil.
Traps are the most common mistake. They catch beetles, but they also pull them in from surrounding yards and concentrate the feeding near the trap. Both University of Maryland Extension and Penn State Extension advise against them for home gardens. Handpicking into soapy water is slower but does not make the problem worse, and it is most effective when done daily. If you are treating grubs, timing matters more than the product: spring applications mostly miss the large grubs that are deep in the soil, and the window for young grubs is late summer.
For the lawn side of the decision, the prevention guide covers soil, water and mowing, and the treatment timing guide explains why season changes the result. The insects hub lists the other invasive insects on the site, and the plants hub covers the species the beetles feed on. Photo credits and licences sit on the image credits page.
Identification
Look for the combination of characters below. A single feature is rarely enough, especially when a native look-alike is present.
- Adult size and color
- About 1/2 inch long, with a metallic green body and coppery-brown wing covers that do not quite reach the tip of the abdomen. Extension descriptions give sizes from about 3/8 to 1/2 inch.
- White tufts
- Five patches of white hair sit along each side of the abdomen, just under the edge of the wing covers. This is the quickest way to separate it from other beetles.
- Grubs
- Creamy white, C-shaped and about 1 inch long when mature, with a tan head and six legs. The pattern of hairs on the rear underside forms a distinctive V shape.
- Adult feeding damage
- Adults chew the soft tissue between the larger veins, leaving a lacy skeleton. Roses, grapes, lindens, crabapples and many other ornamentals are attacked.
- Season
- In the Mid-Atlantic, adults emerge in mid-June to early July and remain active for about four to six weeks. Most egg laying happens in July and tapers off by early August.
- Lawn damage
- Grubs feed on grass roots, and heavy root loss from late August into early October can let turf roll back from the soil like a rug. Damage is worse in drought-stressed lawns.
Look-alikes
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May and June beetle grubs
Phyllophaga species
May and June beetle grubs share the creamy C-shape and brown head. Japanese beetle grubs are slightly smaller when full grown and are separated by the V-shaped pattern of hairs on the rear underside.
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Masked chafer grubs
Cyclocephala species
Masked chafer grubs also feed on turf roots and look much the same from above. The same rear-end hair pattern separates Japanese beetle grubs, and adult chafers lack the five white side tufts.
Range and status
Native range: Japan
Regulatory status by state
No state regulatory classification has been verified for this species yet. Check the current noxious-weed list for your state before making a regulatory decision.
Why it matters
Adult Japanese beetles feed on the foliage, flowers and fruit of more than 300 plant species, and a heavy infestation can strip a rose or a grapevine in days. The grubs feed on grass roots and can kill patches of lawn. The beetle is established across most of the eastern United States and continues to spread.
Management
Handpick adults
Hold a container of soapy water under a branch and tap the branch so beetles drop in, or pick them off by hand. Colorado State University Extension recommends doing this daily, and suggests evening as the most productive time because beetles fly and colonize plants during the day.
Do not rely on traps
Yellow floral and pheromone traps catch large numbers, but they also draw beetles from the neighborhood and concentrate damage nearby. University of Maryland Extension reports a 31 to 40 percent increase in damage to plants next to traps and does not recommend them. Penn State Extension notes the traps catch only about 75 percent of the beetles they attract.
Make the lawn less inviting
Timing: Late June through July, when eggs are being laid.
Mow taller to encourage deeper roots, water deeply and less often, and let the turf go dormant from late June to late July. Female beetles lay eggs in moist soil, and frequent shallow watering favors egg and young grub survival.
Check the lawn before you treat
Timing: Late summer, while the grubs are still near the surface.
Grub damage shows up as loose turf that can be rolled back from the soil, and it is worse in drought-stressed lawns. Brown patches can also come from drought or disease, so lift a section of turf and look at the roots before buying a grub product. Penn State Extension notes that late-summer grub damage is often not noticed until spring, and that spring is the wrong time to treat because the grubs are large and deep.
Consider grub biocontrols
Beneficial nematodes in the genera Heterorhabditis or Steinernema, milky spore (Paenibacillus popilliae) and Bacillus thuringiensis galleriae are options Penn State Extension describes for grubs. Milky spore works only on Japanese beetle grubs and builds up slowly in the soil.
If you spray adults, expect to repeat
Insecticides give only temporary relief when beetles are abundant, and new growth is not protected. Repeated applications may be needed on roses and grapes. Follow the product label; the label is the law, and do not spray open flowers where pollinators are working.
Sources
Facts on this page were checked against the sources below. Each link shows the date the source was accessed.
- Japanese Beetle — National Invasive Species Information Center Accessed November 3, 2026
- Japanese Beetles in the Home Garden — Penn State Extension Accessed November 3, 2026
- Japanese Beetles on Trees, Shrubs, and Flowers — University of Maryland Extension Accessed November 3, 2026
- Japanese beetle in ornamentals — Colorado State University Extension Accessed November 3, 2026
Related pages
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Spring Invasive Plants Checklist: What to Look For in March, April, May and June
Spring invasive plants checklist: what to look for and act on each month from March through June, with links to species and removal guides.