Agrilus

Identification to species within Agrilus requires examination of male genitalia for definitive determination, as many species are morphologically cryptic. Some species groups exhibit distinctive color patterns, such as black elytra with red pronota (e.g., A. audax, A. vittaticollis, A. fuscipennis, A. benjamini), or purplish-red ground coloration with complex golden setal patterns on elytra (e.g., A. turnbowi, A. andersoni, A. howdenorum). Ventral characters may provide diagnostic separation: A. audax possesses a prosternum with sides not bent downward to sharp points (in contrast to A. vittaticollis), a moderately depressed and uniformly pubescent frons (versus deeply depressed with pubescence restricted to lower half in A. benjamini), and males exhibit a deep, smooth, elongate depression on sternite (obsolete in A. benjamini). Sexual dimorphism occurs in A. walsinghami: males are bronzy-brown with coppery reflections on head and pronotum and brassy elytra with purplish tints, while females are larger, more robust, and uniformly blue to greenish blue above.

Habitats span diverse environments across all continents except Antarctica, with highest diversity in tropical and warm temperate regions. Species occupy forests, woodlands, and shrublands where host plants occur. Larval development occurs in woody substrates: primarily dead twigs and branches, though some species mine living tree trunks, crowns, and main roots. Late-season activity occurs in western North American aridlands, particularly associated with woody Asteraceae such as rabbitbrush in response to monsoon rainfall patterns.

Cosmopolitan distribution excluding Antarctica. In North America, occurs from Canada through the United States to Mexico, with particular diversity in the southwestern U.S. and Mexico. Western U.S. records include British Columbia to Baja California and east to Colorado. Midwestern and eastern records include Texas, Oklahoma, Missouri, Illinois, Ohio, Kansas, and Nevada.

Adult activity predominantly spring and early summer across most of range. Late summer and early fall activity documented in western aridlands, particularly July through September for A. walsinghami. Bimodal activity patterns occur in south Texas due to spring and fall rains. Seasonal timing varies with host plant phenology and regional precipitation patterns.

Larvae feed on wood of host plants, primarily in dead twigs and branches. Adults feed on foliage of larval hosts; some species feed on flower petals.

• Ulmus rubra - larval hostslippery elm, living wind-thrown branches, recorded for A. audax
• Quercus macrocarpa - larval hostbur oak, beaten from foliage, primary host for A. audax
• Diospyros virginiana - larval hostpersimmon, larval host for A. fuscipennis
• Amelanchier - larval hostserviceberry, host for A. vittaticollis
• Hibiscus - larval hostwild hibiscus, crown of living plants, host for A. concinnus
• Sphaeralcea - suspected larval hosthost for A. malvastri, unconfirmed
• Callirhoe involucrata - larval hostwinecup, presumed host for A. muticus, adults feed on petals
• Eriogonum - larval hostconfirmed host for A. blandus, adults visit flowers
• Ericameria nauseosa - presumed larval hostgray rabbitbrush, adults exclusively associated, host unconfirmed for A. walsinghami
• Phoradendron - larval hostmistletoe, hemiparasitic on mesquite and other woody hosts, recorded for A. turnbowi, A. andersoni, A. howdenorum
• Prosopis glandulosa - indirect hostmesquite, host for mistletoe that supports A. turnbowi

Larval development occurs within woody host tissue. Most species develop in recently dead twigs and branches; some species mine living tree trunks, crowns, and main roots. Pupation occurs within the larval gallery. Adults emerge and are typically found on foliage of larval hosts. Species developing in living hosts are more difficult to rear than those in dead wood, as infested material cannot simply be collected and held for emergence.

Adults are most commonly encountered on foliage of larval host plants, typically not visiting flowers (unlike related genera Acmaeodera and Anthaxia). Exceptions include A. muticus, found almost exclusively in flowers of winecup where adults feed on petals and mate, and A. blandus, frequently encountered on flowers of Eriogonum. Adults of some species exhibit escape behavior when disturbed. Late-season species in western aridlands demonstrate activity patterns synchronized with monsoon rainfall.

Larvae function as wood decomposers in dead branches and twigs, contributing to nutrient cycling. Species attacking living trees may act as secondary pests, exploiting trees under biotic or abiotic stress. Some species serve as indicators of host plant distribution and habitat quality. No known associations with conifers have limited expansion into boreal forest ecosystems.

Several species are significant economic pests in forest and ornamental landscapes: Agrilus anxius (bronze birch borer), A. bilineatus (twolined chestnut borer), and A. planipennis (emerald ash borer). The latter, an invasive species in North America, has caused extensive mortality of ash trees. Most pest species have been facilitated by human activity—through introduction of exotic species or cultivation of exotic host plants. The genus is popular among insect collectors due to metallic coloration, though many species are small and cryptically colored compared to other Buprestidae.

• AcmaeoderaAdults routinely visit flowers and exhibit aposematic coloration mimicking stinging Hymenoptera; distinguished from Agrilus by flower-visiting behavior and elytral markings
• AnthaxiaAdults regularly visit flowers; distinguished by different host associations and morphological characters
• AgrilaxiaAdults occasionally visit flowers; smaller and less speciose genus with different morphological features
• ParagrilusClose relative with species associated with Malvaceae; adults normally found on foliage rather than flowers

• Buprestidae
• jewel beetles
• wood-boring beetles
• hyperdiverse genus
• forest pests
• host specificity
• angiosperm associates

• BugGuide
• Two new species of Agrilus from Mexico | Beetles In The Bush
• GBCT Beetle #2: Agrilus walsinghami | Beetles In The Bush
• Agrilus fuscipennis on Persimmon | Beetles In The Bush
• A flower visiting jewel beetle that is not an Acmaeodera | Beetles In The Bush
• Josef Knull was wrong! | Beetles In The Bush