Cotinis nitida (Linnaeus, 1764)

Sub family: Cetoniinae / Tribe: Gymnetini / Genus: Cotinis

Large dorsoventrally flattened beetles, body length: 15-27mm, 8.5-15.5mm wide. Dosal body (apart from shiny head) matte/velvet, colouration variable, usually green with tawny yellow areas. Body metallic green ventrally, occasionally copper. Hind femora pale, distinct from tibia and other ventral surfaces. Pronotum and elytra appearing completely smooth and lacking punctations. Pronotum projecting basomedially over the scutellum, nearly completely concealing it from view. Clypeus with apex emarginate/subquadrate, and bearing a frontal denticle (clypeal horn). Frons developed into a forward projecting longitudonal process. Mesepimeron visible from above. Posthumeral emargination of the eltra distinct. Forwardly projecting mesometasternal process present. Pygidium bicoloured, apical portion testaceous, basal portion green.

The genus Cotinis contains 29 species across 3 subgenera. The typical subgenus Cotinis contains most of the species.

Cotinis is the only member of Gemnetini tribe that contains a frontal clypeal horn. All species of Cotinis also lack dorsal scales, that can be present in other tribal members.

Considerable variation in morphological features have been recognised in Cotinis mutabilis and Cotinis nitida making identification done solely on dorsal colouration and pattern impossible. The two species can be separated from each other by differences in body length (C. nitida: 15-27mm, C. mutabilis: 17-34mm), pygidium colouration (C. nitida: bicoloured with an apical testaceous area, C. mutabilis: unicolorous), and metafemur colouration (C. nitida: pale, C. mutabilis: same colour as tibia). The clypeal horn of C. nitida is usually not as large as what is seen in C. mutabilis. Strut-like ridge between clypeus clypeal horn seen in C. mutabilis are commonly absent or greatly reduced in C. nitida.

Commonly known as the Green June Beetle, adult Cotinis nitida beetles are known to feed on a wide range of thin skinned fruits including grapes, corn, apples, pears, peaches and berries. They are a recognised serious pest for the damage they cause both in larval and adult forms. They commonly have one generation per year, and can overwinter as mature larvae. They are slow flying, creating an audible buzz similar to a bumble bee.

Larvae are pests of pastures, hayfields, lawns and golf courses. The damage caused is through feeding on organic matter around the grass roots, disrupting the root/soil interface and limiting the plants ability to absorb water.

The presence of Popillia japonica has also been recorded as facilitating and increasing the pest status of Cotinis nitida. By feeding on intact grape fruits P. japonica in the United States have allowed fruit to be exploited by Cotinis nitida, whose mouthparts would have otherwise been unsuited to feed on the under ripe fruit (Hammons et.al. 2009). Injured fruit can also produce attractant volatiles causing potential for further fruit damage by increasing the number of beetles present.

Cotinis nitida is native and common through much of the Eastern United States, and west into Texas, Oklahoma and Kansas. It is absent from Australia.

Texas A&M Fact Sheet: http://agrilife.org/winegrapes/files/2015/11/GJB_factsheet.pdf

Brandhorst-Hubbard, J.L., Flanders, K.L., Appel, A.G. 2001. Oviposition site and food preference of the green June beetle (Coleoptera: Scarabaeidae). Journal of Economic Entomology 94(3): 628-633.

Goddrich, M.A. 1966. A revision of the genus Cotinis (Coleoptera: Scarabaeidae). Annals of the Entomological Society of America, 59(3): 550-568

Hammons D.L., Kurtural S.K., Newman M.C., Potter D.A. 2009. Invasive Japanese beetles facilitate aggregation and injury by a native scarab pest of ripening fruits. Proc Natl Acad Sci USA. 2009 Mar 10;106(10):3686-91. doi: 10.1073/pnas.0811097106.

Woodruff, R.E. 2008. The genus Cotinis Burmeister in the eastern United States, with description of a new species from the Florida Keys, including a checklist of the genus (Coleoptera: Scarabaeidae: Cetoniinae) Insecta Mundi 0051: 1-13