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How to identify it
- Adults are a little under 1/2 inch long, with a metallic green head and thorax and copper-brown wing covers.[2][1][3][5]
- Five tufts of white hair line each side of the abdomen, with two more at the tip. APHIS describes the side row as six small tufts.[5][3][1]
- Grubs are C-shaped, white to cream with a tan head, and about 1 inch long when grown. A V-shaped pattern of small spines on the underside of the tip of the abdomen separates them from other lawn grubs.[5][3][1][2]
- Adults feed in groups on warm, sunny days, often starting at the top of a plant in full sun and working down.[2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| May and June beetles | Plain light to dark brown, fly at night and come to lights, while Japanese beetles are metallic green daytime fliers.[5][6] |
| Other white grubs in lawns | Masked chafer and May or June beetle grubs look much the same to the eye; only the spine pattern on the underside of the last segment tells them apart.[5][3] |
Where it lives
Native to Japan and first found in New Jersey in 1916, it is now established through most of the eastern and central United States and in parts west of the Mississippi River.[1]
Biology and life cycle
Adults emerge from the soil in late June or early July. Kentucky says activity is most intense over 4 to 6 weeks, and individual beetles live about 30 to 45 days.[2][3][7]
Females leave plants to burrow a few inches into the soil and lay eggs, then return to feed, repeating this until they have laid 40 to 60 eggs. They favor moist, grassy areas such as irrigated lawns, and dry soil cuts egg survival.[2][1][3]
Eggs hatch in one to two weeks (NC State gives 8 to 9 days, Minnesota about two weeks), and the grubs feed on roots, growing through three stages and reaching nearly full size (about 1 inch) by late August.[7][3][2]
When the soil cools to about 60°F in fall the grubs move deeper; most winter 2 to 6 inches down, and they go inactive at about 50°F.[2][1]
In spring the grubs return to the root zone to feed, then pupate; adults emerge about 2 weeks later. There is one generation a year.[1][2][5][7]
Beetle-damaged leaves give off odors that draw more beetles, which is why clusters build up on some plants while equally attractive neighbors are only lightly hit.[3]
Damage and signs
- Adults feed on more than 300 kinds of plants, chewing out leaf tissue between the veins so leaves look lacy or skeletonized; they also eat flowers and chew holes in fruit.[1][2][3][4][7]
- Roses, grapes, lindens, sassafras, Norway maple, Japanese maple, purple-leaf plum and many flowering crabapples are especially prone to damage; Minnesota adds birch, elm, raspberry, basil and hollyhock among others.[2][3]
- Most adult damage is cosmetic. Healthy, mature trees and shrubs tolerate a lot of feeding, but young or weak plants can be stunted or even killed by severe, repeated feeding.[3]
- Grubs chew off grass roots, causing dead patches where the sod can be rolled back like a carpet, often showing up in mid-to-late August.[1][2][3]
- Skunks, armadillos, raccoons, moles, crows and other animals may tear up grub-infested turf while foraging.[5][3]
Health risk
Japanese beetles are plant pests; their harm is to lawns, gardens and landscape plants. The one human problem in the medical literature is unusual: a 2020 case report describes an adult beetle lodged in the ear of a 14-year-old, and the authors note that insects in the ear canal can cause significant pain and distress.[1][8]
Control
Prevention
Where the beetle is common, choose landscape plants it rarely attacks; APHIS lists red maple, boxwood, hosta and begonia among resistant choices.[1][2]
Start when the first beetles appear and keep going; Minnesota says they feed for six to eight weeks and are harder to manage once numbers build.[3]
Traps and physical control
On small plantings, knock beetles into a bucket of soapy water in the morning or evening while they are sluggish, and check daily: removing them also reduces the odors that draw more beetles.[2][3]
Cover prized plants such as roses with fine netting at peak activity, but don't cover plants in bloom that need pollinators.[2][3]
Japanese beetle traps draw in many more beetles than they catch, so in most yards they do more harm than good; if used, place them well away from plants.[2][3][7]
Biological control
For grubs, milky spore disease and beneficial nematodes are biological options. NC State says milky spore works only against Japanese beetle grubs, is best applied in late September or early October to soil with a pH between 6 and 7, and acts slowly but lasts for years.[5][7]
Pesticides
Kentucky says pyrethroids labeled for the plant generally protect foliage for 2 to 3 weeks and carbaryl for 1 to 2 weeks; neem products deter feeding for only about 3 to 4 days, and soap, garlic and hot pepper extracts work poorly.[2]
Preventive grub products such as imidacloprid or chlorantraniliprole go on in April or May; curative trichlorfon goes on in July or August. Water granules in right away.[5]
Adults and grubs need separate plans
Adult beetles can fly in from several miles away, so treating the lawn for grubs won't protect your roses from adult feeding.[2][3]
Healthy, unstressed turf can usually tolerate about 10 Japanese beetle grubs per square foot; Clemson suggests 6 to 8 as a safer trigger where digging animals are a problem.[5][3]
Spreading beyond North America
Native to Japan, where Minnesota notes it is not a major pest, the beetle was first found in New Jersey in 1916. In Europe it was found in northern Italy in 2014 and Switzerland in 2017, and a 2023 review put the outbreak at more than 16,000 square kilometers of northern Italy and southern Switzerland.[3][1][9][10]
A French risk analysis rated the chance of entry and spread as high, through natural spread, trade in plants with soil attached, and hitchhiking beetles. In the United States, APHIS regulates air cargo to keep hitchhiking adults from reaching Western states.[9][1]
Where sources disagree
Size: Kentucky gives 7/16 inch, APHIS a little less than half an inch, Clemson 0.3 to 0.5 inch, and NC State about 5/8 inch (16 mm).[2][1][5][7]
Egg depth: Minnesota says females tunnel one to three inches into the soil, Kentucky 2 to 3 inches, APHIS about 3 inches, and NC State 2 to 6 inches.[3][2][1][7]
How far adults fly: Clemson says about half a mile, while Kentucky and Minnesota say several miles.[5][2][3]
Common questions
- Do Japanese beetle traps work?
- Not for protecting plants. University of Kentucky research found the traps attract far more beetles than they catch, so nearby plants often suffer more damage than with no trap, and NC State says traps have no real impact on the next year's grubs.[2][11]
- Will grub control in my lawn stop the beetles on my plants?
- No. Adults are strong fliers drawn to favored plants from a distance, so lawn grub control won't prevent adult feeding.[2][7]
- Why are Japanese beetles regulated?
- USDA APHIS regulates air cargo to keep hitchhiking adult beetles from reaching Western states, and Minnesota restricts moving the beetle out of the state.[1][3]
- Does milky spore work on Japanese beetle grubs?
- It can. Milky spore is a soil bacterium that grubs swallow while feeding; it works only against Japanese beetle grubs and acts slowly, but once established it can spread on its own.[7][5]
Sources
- USDA Animal and Plant Health Inspection Service, “Japanese Beetle (last modified September 26, 2025).” www.aphis.usda.gov/plant-pests-diseases/japanese-beetle (accessed 2026-11-11)
- University of Kentucky Entomology, “ENTFACT-451: Japanese Beetles in the Urban Landscape (revised March 2026).” entomology.mgcafe.uky.edu/ef451 (accessed 2026-11-11)
- University of Minnesota Extension, “Japanese beetles in yards and gardens.” extension.umn.edu/yard-and-garden-insects/japanese-beetles (accessed 2026-11-11)
- Annual Review of Entomology, via PubMed, “Potter and Held (2002), Biology and management of the Japanese beetle.” pubmed.ncbi.nlm.nih.gov/11729073/ (accessed 2026-11-11)
- Clemson Cooperative Extension Home & Garden Information Center, “White Grub Management in Turfgrass (HGIC).” hgic.clemson.edu/factsheet/white-grub-management-in-turfgrass/ (accessed 2026-11-11)
- University of Wisconsin-Madison Extension, “May/June Beetles (XHT1240).” hort.extension.wisc.edu/articles/mayjune-beetles/ (accessed 2026-11-11)
- NC State Extension, “Japanese Beetle.” content.ces.ncsu.edu/japanese-beetle (accessed 2026-11-11)
- Cureus, via PubMed, “Schwanke et al. (2020), Adult Popillia japonica as an otorhinolaryngologic invasive foreign body in a rural area.” pubmed.ncbi.nlm.nih.gov/33447476/ (accessed 2026-11-11)
- Frontiers in Insect Science, via PubMed, “Poggi et al. (2022), A nationwide pest risk analysis in the context of the ongoing Japanese beetle invasion in Continental Europe: the case of metropolitan France.” pubmed.ncbi.nlm.nih.gov/38468800/ (accessed 2026-11-11)
- Frontiers in Insect Science, via PubMed, “Gotta et al. (2023), Popillia japonica: Italian outbreak management.” pubmed.ncbi.nlm.nih.gov/38469512/ (accessed 2026-11-11)
- NC State Extension, “White Grubs in Turf.” content.ces.ncsu.edu/white-grubs-in-turf (accessed 2026-11-11)
- iNaturalist, “Popillia japonica taxon page (order and family).” www.inaturalist.org/taxa/67760 (accessed 2026-10-06)