Agrilus audax

Distinguished from similar species Agrilus vittaticollis by prosternal structure: A. audax has normally shaped prosternal sides, while A. vittaticollis has sides bent downward to sharp points. Differs from A. benjamini by frons structure: A. audax has moderately depressed, uniformly pubescent frons versus deeply depressed frons with pubescence restricted to lower half in A. benjamini. Male A. audax identified by deep, smooth, elongate sternal depression, versus obsolete depression in A. benjamini males. Large size and bold black-red coloration separate it from most other Agrilus species.

Large-bodied Agrilus species with distinctive coloration: black elytra contrasting with bright red pronotum. Pronotum features a densely pubescent median channel. Prosternum with sides normal, not bent downward to sharp points (distinguishing it from A. vittaticollis). Frons moderately depressed and uniformly pubescent. Males possess a deep, smooth, elongate depression on the sternite. Body size and bold color pattern make it visually conspicuous among Agrilus species.

Hardwood forests and woodlands; specifically associated with living or recently wind-thrown branches of bur oak (Quercus macrocarpa) and slippery elm (Ulmus rubra). Collected from standing trees and fresh slash piles. Habitat specificity contributes to rarity of encounters.

North America: documented from Texas (type locality), Arizona, Missouri, Oklahoma, and Ohio. Illinois record exists but remains unconfirmed. Distribution appears discontinuous and patchy, reflecting both genuine rarity and specialized habitat requirements.

Adults active during summer months; specific phenology poorly documented due to scarcity of records. July-August collecting trips in Arizona and New Mexico suggest peak activity during monsoon season in southwestern portion of range.

• Quercus macrocarpa - larval hostbur oak; larvae develop in living or recently wind-thrown branches
• Ulmus rubra - larval hostslippery elm; first documented host for the species

Adults have been collected by beating branches of host trees. Larvae are wood-borers, developing in living or recently damaged hardwood branches. Specific behaviors such as mating, dispersal, or host-finding remain undocumented due to extreme rarity of observations.

Primary consumer as larva, acting as wood-borer in living hardwood branches; contributes to nutrient cycling and structural heterogeneity in oak-elm woodland ecosystems. Specific ecological interactions remain unstudied.

Of interest to coleopterists and buprestid specialists as one of North America's rarest and most sought-after jewel beetles. Historical misidentifications, including one by renowned entomologist Josef Knull, illustrate challenges of species recognition in this group. No economic or medical significance documented.

• Agrilus vittaticollisShares large size and black-red color pattern; distinguished by prosternal sides bent downward to sharp points, versus normal sides in A. audax
• Agrilus benjaminiSimilar coloration and body form; distinguished by deeply depressed frons with pubescence only on lower half, and males with obsolete sternal depression

Josef Knull, prominent North American coleopterist, misidentified two specimens of A. audax as A. vittaticollis in 1949 and 1953—after having correctly reported the species from Missouri. This illustrates that even experienced specialists can overlook rare species, and that A. audax may be underreported due to such misidentifications.

• rare
• wood-borer
• oak-associated
• elm-associated
• misidentification history
• jewel beetle
• North America
• hardwood forest

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Josef Knull was wrong! | Beetles In The Bush
• Insect Identifications and Etiquette | Beetles In The Bush
• entomologists | Beetles In The Bush | Page 3