Popillia japonica

Distinguished from the larger Green June Beetle (Cotinis nitida, 15–27 mm) by smaller size, metallic copper elytra, and white abdominal tufts. Green June Beetles are matte green, lack white tufts, and have a distinctive flight sound. Distinguished from Emerald Flower Scarab (Euphoria fulgida, 13.4–19.8 mm) by smaller size and presence of white tufts; E. fulgida is more variable in color and quicker to fly. Distinguished from Dogbane Leaf Beetle (Chrysochus auratus) by family-level characters: P. japonica has lamellate antennae and spurred hind legs, while C. auratus has long, uniformly segmented antennae, no leg spines, and feeds exclusively on dogbane. The striated elytra and white abdominal tufts are diagnostic for P. japonica among common lookalikes.

Urban and suburban landscapes, agricultural fields, orchards, vineyards, and turfgrass areas. Adults occur on foliage of host plants. Larvae develop in soil, particularly in well-watered turf and areas with organic matter. In Switzerland, colonizes areas near transportation networks including airports, highways, and railways.

Native to Japan (Honshu, Hokkaido, Kyushu, Shikoku). Invasive in North America: established in 28 U.S. states and three Canadian provinces (Ontario, Quebec, British Columbia), with detections in 13 additional states. First detected in New Jersey in 1916. Present in Azores (all islands except Santa Maria since 1970s). In Europe: detected in Italy in 2014 (near Malpensa Airport), spread to Piemont and Lombardy; detected in Switzerland in 2017 (Ticino), with subsequent detections in 2023 near Zürich Airport, Basel, and Valais, and further spread in 2024 to multiple additional cantons. Climate models predict northward expansion into northern New England, upper Midwest, and Canada.

Adults emerge in mid-summer, typically late June through July in North America, with peak abundance in early July. Larval stage present in soil year-round, with feeding damage to roots most severe in late summer and early fall.

Highly polyphagous. Adults feed on foliage, flowers, and fruits of over 300 plant species. Preferred hosts include grape (Vitis), rose (Rosa), linden (Tilia), apple (Malus), cherry (Prunus), hops (Humulus), birch (Betula), crape myrtle (Lagerstroemia), canna (Canna), and zinnia (Zinnia). Adults are "skeletonizers," consuming leaf tissue between veins and leaving a net-like pattern. Larvae feed on roots of grasses and other plants, with strong preference for turfgrasses.

• Vitis vinifera - hostwild grape, preferred host
• Rosa spp. - hostpreferred host; yellow and white varieties more attractive than red or orange
• Tilia spp. - hostlinden, preferred host; varieties with densely hairy leaves less preferred
• Malus spp. - hostapple
• Prunus spp. - hostcherry, peach
• Zea mays - hostcorn; adults clip silks, interfering with pollination
• Glycine max - hostsoybean; defoliation of leaf tissue
• Istocheta aldrichi - parasitoidtachinid fly, specialist parasitoid; lays eggs on beetle pronotum
• Tiphia vernalis - parasitoidspring tiphia wasp, introduced biological control agent; female wasp paralyzes grub and lays egg on it
• Bacillus popilliae - pathogenmilky spore disease, biological control agent
• Steinernema carpocapsae - pathogenentomopathogenic nematode, biological control agent
• Heterorhabditis spp. - pathogenentomopathogenic nematode, more effective than S. carpocapsae against grubs

Complete metamorphosis with one generation per year. Eggs laid in soil, typically in turfgrass areas. Larvae (white grubs) develop underground, feeding on roots through late summer and fall, overwintering in soil, and resuming feeding in spring. Pupation occurs in soil in late spring. Adults emerge in mid-summer, feed, mate, and lay eggs. In Japan, voltinism may vary; in North America, univoltine.

Adults are strong fliers and highly mobile, quickly dispersing across landscapes. When disturbed, adults flare hind legs outward and upward, presenting spurs in a defensive posture; can deliver a sharp prick if handled. Adults aggregate for feeding and mating, attracted by plant volatiles released by damaged foliage combined with female sex pheromones. This aggregation behavior creates localized feeding frenzies. Adults are diurnal and most active in warm, sunny conditions. Hand-picking is most successful in early morning or late evening when beetles are less active. Larvae remain in soil, moving vertically in response to temperature and moisture.

Invasive pest causing significant economic damage to agriculture, horticulture, and turfgrass industries. Adult feeding defoliates plants and reduces photosynthetic capacity; larval feeding damages root systems and compromises plant stability. Estimated potential annual damage costs in Europe of €30 million to €7.8 billion from unmanaged infestations. Serves as host for introduced and native parasitoids and pathogens deployed in biological control programs. Adult aggregation and feeding can indirectly benefit other herbivores by creating additional feeding opportunities on damaged plants.

Major agricultural and garden pest requiring active management. Control methods include hand-picking into soapy water, foliar insecticides, soil-applied insecticides targeting larvae, biological control agents (milky spore disease, parasitoid wasps, entomopathogenic nematodes), and pheromone traps. Traps are effective for monitoring but often increase local damage by attracting more beetles than they capture. Listed on EU Priority Pest List; designated quarantine organism in Switzerland. Historical control attempts included paid bounties and aerial arsenic sprays. Geraniums (Pelargonium) cause temporary paralysis in adults, but beetles resume feeding after recovery.

• Cotinis nitidaGreen June Beetle is larger (15–27 mm), matte green without copper elytra, lacks white abdominal tufts, and produces audible flight sound. Native to North America.
• Cotinis mutabilisFig Beetle is larger, lacks white tufts, and has different wing articulation allowing flight with elytra closed. Native to southwestern North America.
• Euphoria fulgidaEmerald Flower Scarab is larger (13.4–19.8 mm), more variable in color (purple, turquoise), lacks white tufts, and is quicker to take flight.
• Chrysochus auratusDogbane Leaf Beetle is similar in size and metallic coloration but belongs to family Chrysomelidae, not Scarabaeidae; has long segmented antennae rather than lamellate clubs, lacks leg spurs, and feeds exclusively on dogbane.

Frequently misidentified by non-specialists; many green or metallic beetles are erroneously called "Japanese beetles." Pheromone traps are widely misunderstood as effective control tools when they primarily serve monitoring purposes and often increase local infestations. The species does not produce an aggregation pheromone; rather, feeding damage induces plants to release volatile compounds that attract additional beetles.

• invasive species
• agricultural pest
• scarab beetle
• polyphagous
• turf pest
• skeletonizer

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Feasting and frolicking spell trouble when Japanese beetles, Popillia japonica, arrive — Bug of the Week
• New Guide Offers IPM Tips for Japanese Beetles in Soy and Corn
• For Less Bee Bycatch, Leave Geraniol Out of Japanese Beetle Traps
• Climate Change Could Open Doors, Close Others for Spread of Japanese Beetle
• Bug Eric: What is, and is NOT, a Japanese Beetle
• Effective Management Remains Elusive for Beetle That Eats Almost Anything
• The genome of Istocheta aldrichi (Diptera: Tachinidae), a parasitoid of the Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae).
• Population genomics identifies Italian and North American origins of Popillia japonica in Switzerland.