Cotinis

Cotinis species are distinguished from similar scarab beetles by their relatively large size (15–27 mm), matte to slightly iridescent green coloration often with ochre or yellowish markings, and the distinctive Cetoniinae wing mechanism where elytra remain closed during flight. They differ from the smaller, more brilliantly metallic Japanese Beetle (Popillia japonica) by their larger size, less striated elytra, and absence of white abdominal hair tufts. They can be separated from other green scarabs like Euphoria fulgida by their more robust body form and flight behavior. Species-level identification within Cotinis requires examination of specific markings, color patterns, and male genitalia.

Species occupy diverse habitats ranging from sand prairies and xeric dolomite glades to agricultural areas, orchards, and suburban lawns. Adults frequent flowers, sap flows, and fermenting organic matter. Larvae develop in soil, particularly in sandy, well-drained substrates rich in organic matter such as compost, manure, and decomposing vegetation. Specific habitat associations vary by species: C. nitida is strongly associated with turfgrass and agricultural settings, while other species occupy more specialized habitats including tropical forests and Andean ecosystems.

Widespread across the Americas from the United States through Mexico, Central America, and South America. C. nitida occurs primarily in eastern and central North America. C. mutabilis ranges from the southwestern United States through Mexico. South American species include C. columbica (restricted to Andean ecosystems in Colombia), C. lebasi (humid tropical forests), and C. barthelemyi (Colombia and Venezuela). The genus has been recorded from Colombia, Venezuela, and throughout the Neotropical region.

Adult activity peaks in mid to late summer (June–September in temperate regions), with timing varying by latitude and species. Larvae are present in soil during summer months, burrowing deeper in winter. In Missouri, adults have been collected from July through September in ethanol-baited traps.

Adults feed primarily on flower nectar, pollen, and ripe fruit; also attracted to fermenting sap and other fermenting organic matter. Larvae are saprophagous, consuming decaying organic matter, manure, and humus. C. nitida larvae have been observed feeding on decomposing vegetable matter and organic mulches.

Complete metamorphosis with three larval instars. Larvae develop in soil, creating vertical burrows and exhibiting characteristic back-crawling behavior when on the surface. Pupation occurs in soil in late summer. Adults emerge in summer, with some species showing extended emergence periods. Laboratory studies of C. nitida demonstrate significant microbiome shifts between generations when reared on artificial diets.

Adults are diurnal, strong fliers with a distinctive bee-mimicking flight pattern achieved by extending hindwings while elytra remain closed. They aggregate at food sources including sap flows, fermenting fruit, and flowers, with aggregation mediated by olfactory cues from associated yeasts such as Trichosporon cutaneum. When disturbed, adults may buzz loudly but are generally non-aggressive. Larvae exhibit unique locomotion, crawling on their backs with legs upward when moving on soil surfaces, and show negative geotaxis (movement toward the surface). They burrow rapidly when disturbed and demonstrate temperature preferences around 27°C.

Adults function as pollinators while feeding on flowers. Larvae contribute to soil aeration and decomposition of organic matter. The association with fermentative yeasts suggests potential roles in microbial dispersal. As prey, adults are vulnerable to avian predators due to their exposed behavior on mowed lawns and predictable aggregation patterns.

C. nitida and C. mutabilis are recognized pests of agriculture and horticulture. Adults damage ripe fruits (berries, grapes, figs) and occasionally feed on tree sap. Larvae disrupt turfgrass and agricultural soils through burrowing, creating mounds and affecting root systems. Soils with organic mulches and manure applications are particularly attractive to egg-laying females. Frequently mistaken for the more damaging Japanese Beetle, leading to unnecessary control measures. Pheromone traps are commercially available but may attract more beetles than they control.

• Euphoria fulgida (Emerald Flower Scarab)Similar size and metallic coloration, but more variable in color (purple, turquoise in some populations) and quicker, more erratic flight behavior. Euphoria species often show more brilliant metallic luster and different antennal club structure.
• Popillia japonica (Japanese Beetle)Much smaller (8–12 mm), with distinct white abdominal hair tufts, striated elytra, and spined hind tibiae used in defense. Japanese Beetles are serious skeletonizing pests of foliage, whereas Cotinis species primarily damage fruit and are attracted to fermenting matter.
• Strategus antaeus (Smooth Ox Beetle)Larger scarab in same family but different subfamily (Dynastinae); males have distinctive horns, and the species is associated with sandy prairies rather than general agricultural settings.

Cotinis species are frequently misidentified as Japanese Beetles by the public and in media, leading to inappropriate control recommendations. The Green June Beetle (C. nitida) is native to North America and not an invasive species, unlike the Japanese Beetle. Mobile identification apps often compound these errors. Pheromone traps marketed for Japanese Beetles may attract Cotinis species but are not effective control methods for them.

• scarab beetles
• flower chafers
• agricultural pests
• sap feeders
• pollinators
• soil larvae
• fermentation-associated
• bee mimics

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Ascalaphidae | Beetles In The Bush
• August | 2022 | Beetles In The Bush
• Bug Eric: What is, and is NOT, a Japanese Beetle
• Party on a pin oak | Beetles In The Bush
• entomology | Beetles In The Bush | Page 5
• From the mailbag – Who’s that large dead insect on the driveway? Green June Beetle Grub, Cotinis nitida — Bug of the Week
• Microbiome perturbations during domestication of the green June beetle (Cotinis nitida)
• The Behavior of the Larvae of Cotinis Nitida Burmeister. (Coleoptera)
• The Role of Trichosporon cutaneum in Eliciting Aggregation Behavior in Cotinis nitida (Coleoptera: Scarabaeidae)
• A new species and first record of Cotinis Burmeister (Coleoptera: Scarabaeidae: Cetoniinae) for Venezuela
• Synopsis and potential geographical distribution ofCotinis(Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini) in Colombia
• Synopsis and potential geographical distribution of <i>Cotinis</i> (Coleoptera: Scarabaeidae: Cetoniinae: Gymnetini) in Colombia
• The behaviour of Cotinis nitida Linnaeus, the green June beetle (Coleoptera: Scarabaeidae), on mowed lawns makes them especially vulnerable to bird predators
• The mating system and parental behaviour of the green June beetle (Cotinis nitidaLinnaeus) (Coleoptera: Scarabaeidae) are exploited by avian predators
• Gut bacteria of adult and larval Cotinis nitida Linnaeus (Coleoptera: Scarabaeidae) demonstrate community differences according to respective life stage and gut region