Japanese beetle: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It does not identify what is wrong with any tree and does not say what should be done about one. The Japanese beetle, Popillia japonica, is a leaf-eating beetle whose grubs live in the soil. Each section names its source, all read on October 9, 2026. The parent page, insect pests of trees, compares it with the other pests on the list.

Names and origin

The Canadian Food Inspection Agency, called CFIA, gives the scientific name Popillia japonica (Newman) and says the beetle was introduced to eastern North America from Japan in 1916, and to Canada in 1939. The University of Kentucky's entomology department says it was first found in the United States in 1916 after an accidental introduction into New Jersey, and that it was known only from Japan before then, where it is not a major pest. Defra, the United Kingdom's department for farming and the environment, describes it as a chafer beetle native to Japan, regards its first mainland Europe incursion as large numbers of adults found near Milan, Italy, in autumn 2014, and notes it was introduced to the Azores in the 1970s.

What the sources say to look for

Kentucky describes the adult as a 7/16-inch metallic green beetle with copper-brown wing covers and a row of white hair tufts along each side. Defra gives the length as 8 to 11 mm and counts five white tufts on each side plus two on the last abdominal segment, which it names as the feature separating the beetle from British chafers. Kentucky says adults feed in groups, starting at the top of a plant, on the upper leaf surface, chewing out tissue between the veins so the leaf looks lacelike or skeletonized, and that severely injured trees look scorched by fire. CFIA gives the same skeletonizing description and says attacked leaves wither and die, and that adults also attack flower buds and fruit. Defra adds that leaves may turn brown and fall.

Kentucky calls the grubs white, and Defra describes the larvae as C-shaped. CFIA says that when the larvae feed on grass roots the result is patches of brown dead grass that may feel spongy and pull away easily, and Kentucky says damaged sod can be rolled back like a carpet. Defra says the symptoms of root feeding are not specific.

Hosts

The counts differ by source. Kentucky says the beetles feed on about 300 plant species; CFIA says more than 300; Defra says over 300 hosts in 79 plant families reported in the USA. CFIA lists as preferred hosts elm trees, maple trees, roses, grapevines, fruit trees including peach, apple, apricot, cherry and plum, and small fruit. Kentucky names as especially prone to damage roses, grapes, lindens, sassafras, Norway maple, Japanese maple and purple-leaf plum, and many flowering crabapples, and says many common trees and shrubs are much less attractive. Defra's tree hosts include maples, birch, beech, European larch, apples, poplars, stone fruit, oak, lime and elms. Defra notes that beetles feeding on trees and shrubs usually lay eggs in nearby grass, so the grubs are tied to turf and pasture.

Life cycle as the sources state it

Kentucky says adults emerge from the ground and begin feeding in June, with activity most intense over 4 to 6 weeks from late June, and that individual beetles live about 30 to 45 days. Females burrow 2 to 3 inches into soil to lay a total of 40 to 60 eggs. The grubs then spend about 10 months in the soil, are nearly full-sized (about 1 inch) by late August, move deeper when the soil cools to about 60 degrees F, and pass the winter 2 to 6 inches down. CFIA places adult damage from late June to mid-October. Defra says one generation a year is usual in southern parts of the United States and that in cooler or mountainous places the cycle can take two years; it expects a mostly two-year cycle in the United Kingdom.

On movement, Kentucky says adults are highly mobile and can infest new areas from several miles away. Defra reports marked beetles found up to 2.75 miles from where they were captured, and says adults and larvae can move in the plant trade, adults can hitchhike on vehicles and the cryptic larvae could easily travel with rooted plants.

Where it is reported

Kentucky says the beetle has spread north to Ontario and Minnesota, west to Iowa, Missouri and Arkansas, and south to Georgia and Alabama, and that it infests every Kentucky county; the first Kentucky finds were on the southern edge of Louisville in 1937. CFIA says the beetle is established in Ontario, Quebec, New Brunswick, Nova Scotia and Prince Edward Island. Defra lists its range as Japan, Kunashir Island in Russia, the United States, Canada and Italy.

Regulated status

CFIA (page modified September 17, 2026) says treatment programs have been unable to completely eliminate the beetle from Canada, though annual trapping has been very effective in detecting infestations. It asks that signs of the beetle in Manitoba, Saskatchewan, Alberta or the territories be reported to CFIA. It says British Columbia is the only Category 1 Japanese beetle pest-free area in Canada, that CFIA is working with the provincial ministry, municipalities and industry to prevent spread and keep that status, and that Newfoundland and Labrador is responding to increased detections in the St. John's area. It links directive D-96-15, which sets phytosanitary requirements to prevent the spread of the beetle in Canada and the United States, and a regulatory status page for areas in both countries. No United States order page was read for this profile.

Defra's factsheet (dated June 2016) says the beetle is regulated in the European Union and that the government will take statutory action in the United Kingdom if the beetle is found on imported plants, and against outbreaks at commercial plant-growing sites. It says suspected outbreaks of this or any other non-native plant pest should go to the plant health authority for the part of the United Kingdom concerned. See reporting a pest in the United Kingdom and reporting a pest in Canada for the offices.

Management as the sources list it

Kentucky's page covers plant selection, hand removal, netting, insecticides and traps, and says its research found traps attract many more beetles than they catch, so that plants near traps are likely to suffer more damage than if no traps were used. CFIA points readers to local nurseries for management. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences.