Chrysina

Distinguished from other Rutelinae by the combination of large size, robust body form, and brilliant metallic structural coloration. Separated from the superficially similar genus Plusiotis (now synonymized) by genitalic and other subtle morphological characters. Within the genus, species identification relies on color pattern, body proportions, and male genitalic structure. The metallic iridescence is produced by circularly polarized light-reflecting structures in the elytral cuticle, a feature rare among beetles. Nocturnal activity and strong attraction to ultraviolet and mercury vapor lights are characteristic field traits.

Medium to large scarabs, typically 15–35 mm in length. Body robust and broadly oval. Elytra and pronotum often exhibit brilliant metallic iridescence due to structural coloration from helicoidal stacks of chitin microfibrils in the cuticle. Coloration varies by species and includes silver, gold, green, blue, purple, and copper tones, sometimes with contrasting stripes or maculations. Antennae lamellate, with 10 segments. Legs stout, adapted for climbing vegetation. Sexual dimorphism present in some species, with males often possessing more pronounced horns or tubercles on the head and pronotum.

Montane forests and woodlands, particularly in 'sky island' mountain ranges of the southwestern United States and Mexico. Associated with coniferous and mixed conifer-hardwood forests at moderate to high elevations. Adults frequently found on host trees, especially junipers. Larval habitat consists of decaying logs and stumps in forested areas.

Southwestern United States (Arizona, New Mexico, Texas, southern California) south through Mexico and Central America to northern South America (Colombia, Ecuador). Center of diversity in the mountains of Mexico and Central America. Specific documented localities include the Davis Mountains and Chisos Mountains (Texas), Huachuca Mountains, Chiricahua Mountains, Madera Canyon, and Pinaleno Mountains (Arizona), and numerous mountain ranges in Panama, Colombia, and Ecuador.

Adults active primarily during summer months, with peak activity coinciding with monsoon season in the southwestern United States (July–August). Nocturnal, with greatest activity during the first four hours after sundown.

Adults feed on foliage of juniper trees (Juniperus spp.) and possibly other conifers. Larvae feed on decaying wood in rotting logs and stumps.

Complete metamorphosis with egg, larva, pupa, and adult stages. Larvae develop in decaying hardwood or conifer logs, requiring several years to mature. Adults emerge in summer, with timing varying by elevation and latitude. No detailed life history studies published for most species.

Strictly nocturnal; adults become active shortly after dusk and are strongly attracted to ultraviolet and mercury vapor lights. Adults climb vegetation to feed on foliage. When disturbed, may drop from host plants and feign death. Flight capability well-developed; adults may disperse between mountain ranges.

Larvae contribute to wood decomposition and nutrient cycling in forest ecosystems. Adults function as folivores on coniferous trees, though population densities generally low enough to prevent significant host damage. The genus includes relictual species restricted to Pleistocene cool-wet refugia, making them indicators of historical climate stability and conservation priorities for montane biodiversity.

Highly prized by amateur and professional collectors worldwide due to spectacular metallic coloration. Commercial collection and sale of specimens occurs internationally. Collection pressure, combined with climate change impacts on montane habitats, raises conservation concerns for some species. Chrysina gloriosa is among the most sought-after North American scarabs. No agricultural or economic pest status.

• PlusiotisFormerly recognized as a separate genus; now synonymized with Chrysina based on morphological and molecular evidence. Historical specimens may bear this name.
• CotalpaAnother North American ruteline genus with metallic coloration, but generally smaller, with different antennal club structure and lacking the brilliant jewel-like iridescence of Chrysina.
• ParabyrsopolisShares Rutelinae subfamily and nocturnal habits, but smaller, less robust, and with more subdued coloration; pronotum and elytra proportions differ.

• scarabaeidae
• rutelinae
• jewel scarab
• structural coloration
• nocturnal
• montane
• sky islands
• metallic iridescence
• circularly polarized light
• conservation concern

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Amblycheila cylindriformis on white | Beetles In The Bush
• pleasing fungus beetles | Beetles In The Bush
• A reference quality genome assembly for the jewel scarab Chrysina gloriosa
• A new species of Chrysina Kirby, 1828 (Coleoptera: Scarabaeidae: Rutelinae: Rutelini) from Ecuador and inclusion into proposed veraguana species-group
• A Monographic Revision of The Jewel Scarabs Genus Chrysina from Panama, Colombia, and Ecuador (Coleoptera: Scarabaeidae: Rutelinae: Rutelini)
• Theoretical framework to describe the reflection of circularly polarized light by a natural photonic crystal: elytron of a Chrysina resplendens scarab