Plinthocoelium suaveolens suaveolens

Distinguished from other North American cerambycids by combination of large size, brilliant iridescent green elytra with coppery pronotum, and extraordinarily long black antennae and legs with orange femora. Separated from western subspecies P. s. plicatum by bronze/cupreous tints and weak transverse rugae on pronotum (plicatum has stronger rugae and different color tones). Differs from related Callichroma species by leg coloration and pronotal sculpture. No other North American cerambycid matches this combination of size, color, and proportions.

Large, elongate beetle with brilliant metallic coloration. Elytra iridescent emerald green to blue-green. Head and pronotum coppery or bronze with weak transverse rugae. Antennae extremely long, black, often exceeding body length in males. Legs black with vivid orange femora, creating striking contrast. Body length approximately 20–30 mm. Pronotum with small lateral tubercles. Elytra finely punctured, tapering slightly toward apex.

Associated with xeric to dry-mesic habitats supporting host plant Sideroxylon lanuginosum, including dolomite and rhyolite glades, dry oak woodlands, and cedar glades. Adults found on host tree trunks, flowers, and occasionally at fermenting baits. Larval habitat is roots of living host trees, particularly where roots emerge from soil near trunk base.

Southeastern and south-central United States: Florida, Georgia, Alabama, Mississippi, Louisiana, Arkansas, Missouri, Oklahoma, Kansas, and northeastern Texas. The nominate subspecies suaveolens occupies the eastern portion of the range, intergrading with subspecies plicatum in northeastern Texas.

Adults active primarily July through August in most of range; Missouri records extend into September. Peak activity during hottest part of day (2–4 PM). Larvae develop over multiple years in host roots.

Larvae feed internally in roots of living Sideroxylon lanuginosum (gum bumelia), creating granular frass that accumulates at soil surface near trunk base. Adults do not feed; may occasionally visit host flowers or fermenting baits but do not consume solid food.

• Sideroxylon lanuginosum - larval hostGum bumelia; larvae bore in roots of living trees

Complete metamorphosis with prolonged larval development. Eggs deposited in bark crevices near soil line; larvae tunnel into roots and develop for 2–3 years. Mature larvae create pupal cells in root wood; adults emerge through exit holes. Adults live 2–4 weeks, do not feed, focused on reproduction.

Adults are exceptionally wary and alert, among the most difficult North American cerambycids to approach. When disturbed, they rapidly flee by flight, with legs and antennae held outstretched. Often perch on lower trunk of host trees, facing downward. Males attracted to prionic acid lures. Adults sometimes aggregate at host flowers or fermenting baits. Flight period coincides with host flowering phenology.

Primary wood-borer in roots of living Sideroxylon lanuginosum; contributes to nutrient cycling and creates habitat for associated organisms. Larval galleries may weaken host trees. Serves as prey for birds and other insectivores. Adults likely pollinators of host flowers during visitation.

Collected by entomologists for scientific study and private collections due to exceptional beauty. Subject of bait-trapping studies using fermenting wine/ethanol mixtures. Not an agricultural or forestry pest; host plant not commercially important. Occasionally encountered by naturalists and photographers seeking charismatic insects.

• Plinthocoelium suaveolens plicatumWestern subspecies distinguished by stronger pronotal rugae and different color tones; ranges intergrade in northeastern Texas
• Callichroma speciesRelated callichromatines share large size and metallic coloration but differ in leg coloration (often uniformly colored) and pronotal structure
• Chloridolum cinderellumAustralian callichromatine with similar gaudy coloration but geographically isolated and not closely related

• Cerambycidae
• Callichromatini
• bumelia borer
• Sideroxylon
• glade fauna
• xeric habitat
• fermenting bait
• iridescent
• wood-borer

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
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