Agrilus

Curtis, 1825

jewel beetles, metallic woodboring beetles

Species Guides

158

Agrilus is a of jewel beetles ( Buprestidae) containing approximately 3,000-4,000 described , making it one of the largest genera in the animal kingdom. Species are found on all continents except Antarctica and exhibit diverse ecological strategies, though most are wood-boring larvae developing in recently dead branches of woody flowering plants. A few notable species are economically significant pests that attack living trees, including the emerald ash borer (A. planipennis), bronze birch borer (A. anxius), and twolined chestnut borer (A. bilineatus).

Agrilus sulcicollis by (c) Michael Knapp, some rights reserved (CC BY), uploaded by Michael Knapp. Used under a CC-BY license.

Agrilus derasofasciatus by (c) Michael Knapp, some rights reserved (CC BY), uploaded by Michael Knapp. Used under a CC-BY license.

Agrilus cuprescens by (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY), uploaded by Alexis Tinker-Tsavalas. Used under a CC-BY license.

Pronunciation

How to pronounce Agrilus: /ˈæɡrɪləs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Agrilus is distinguished from other Buprestidae by its enormous and generally smaller, less vividly colored compared to genera like Chrysobothris or Acmaeodera. Within the genus, identification is notoriously difficult and often requires examination of male genitalia; many species are distinguishable only by subtle differences in prosternal shape, elytral , or setal patterns. Species with red-and-black coloration (A. audax, A. vittaticollis, A. fuscipennis, A. concinnus) form a recognizable but non- united by large size and striking coloration. Flower-visiting species (A. muticus on Callirhoe, A. blandus on Eriogonum) are exceptional and readily identified by their consistent presence on specific flowers.

Images

Habitat

Primarily associated with woody flowering plants across diverse terrestrial including forests, woodlands, riparian corridors, and urban landscapes. Larval habitats range from recently dead twigs and branches (most ) to living tree trunks and roots (pest species). Some species occupy specialized : A. walsinghami on gray rabbitbrush in western North American scrublands, A. muticus and A. blandus on flowers of herbaceous plants, and A. andersoni/A. howdenorum/A. turnbowi on mistletoe (Phoradendron). No species are associated with coniferous plants.

Distribution

distribution on all continents except Antarctica. Particularly diverse in tropical and temperate regions. North American fauna well-documented through Fisher's 1928 revision and subsequent work; Mexican fauna remains incompletely described with new continuing to be discovered.

Seasonality

activity generally peaks in spring and early summer (May-July in temperate North America), with notable exceptions: A. walsinghami active late July to mid-September; A. concinnus occurs much later in season than most . Some western North American in Sky Islands and lower Rio Grande Valley exhibit bimodal activity patterns coinciding with summer monsoons or spring and fall rains.

Host Associations

Flowering plants (Angiosperms) - larval Primary larval ; wide taxonomic range across diverse plant . No conifer associations known.
Fraxinus (ash) - larval of A. planipennis (emerald ash borer), which attacks living trees
Betula (birch) - larval of A. anxius (bronze birch borer), primarily damaging European birch
Castanea (chestnut), Quercus (oak) - larval of A. bilineatus (twolined chestnut borer), which primarily attacks stressed trees
Diospyros virginiana (persimmon) - larval of A. fuscipennis; larvae mine lower trunks, crown, and main roots of living trees
Amelanchier (serviceberry) - larval of A. vittaticollis
Hibiscus - larval of A. concinnus; larvae develop in base of living plants
Callirhoe involucrata (winecup) - feeding site, presumed larval A. muticus found exclusively on flowers; larval unconfirmed but suspected
Eriogonum - feeding site, larval A. blandus frequently encountered on flowers; Eriogonum confirmed as larval
Phoradendron (mistletoe) - larval of A. turnbowi, A. andersoni, and A. howdenorum; beetles exhibit matching mistletoe foliage
Ericameria nauseosa (gray rabbitbrush) - association, presumed larval Exclusive of A. walsinghami in western North America
Genista aetnensis - probable larval of A. albomarginatus verres in Sicily; numerous specimens collected on this plant

Life Cycle

Holometabolous with wood-boring larvae. Most develop as larvae in recently dead twigs and branches, with emerging to feed on foliage of larval . Development time varies; species attacking living trees (A. planipennis, A. anxius, A. bilineatus) have more complex involving extended larval galleries in phloem and outer sapwood. Some species (A. fuscipennis, A. concinnus, A. vittaticollis) mine lower trunks, crowns, and main roots of living hosts, making them more difficult to rear than dead-wood species.

Behavior

of most are found on foliage of larval plants and do not visit flowers, unlike related Acmaeodera and Anthaxia. Exceptions include A. muticus on Callirhoe flowers and A. blandus on Eriogonum. Adults are strong fliers and some species exhibit in coloration. Some species demonstrate cryptic coloration matching host plants: A. howdenorum has golden setae on resembling Phoradendron leaves. Specimens have been recovered from nests of the crabronid Cerceris fumipennis, which provisions nests with paralyzed Buprestidae.

Ecological Role

Primary decomposers of dead woody material in most , facilitating nutrient cycling in forest . A few species function as secondary pests attacking stressed or dying trees. No known associations with coniferous plants have limited expansion into forests. Some species show plant specificity ranging from monophagy (single plant species) to oligophagy (several related ).

Human Relevance

Several are significant economic pests: A. planipennis (emerald ash borer) is a destructive pest of ash trees in North America; A. anxius (bronze birch borer) damages ornamental birch; A. bilineatus (twolined chestnut borer) affects chestnut and oak. The enormous diversity and taxonomic difficulty of the presents challenges for identification and pest management. Some species are sought by collectors; A. walsinghami specimens have sold for over $16.

Similar Taxa

AcmaeoderaBoth are diverse Buprestidae , but Acmaeodera routinely visit flowers and often have bold yellow/red elytral patterns with -mimicry; Agrilus adults are primarily foliage-associated and generally less vividly colored
ChrysobothrisBoth contain wood-boring , but Chrysobothris are often larger with more spectacular metallic colors and some species utilize coniferous ; Agrilus is distinguished by its vastly greater and generally smaller size
ParagrilusClose relative with similar ; some Paragrilus share Malvaceae associations with herbivorous Agrilus species, but Paragrilus is less speciose and are normally found on foliage rather than flowers
AgrilaxiaSimilar small size and appearance; historically confused with Agrilus (e.g., A. obsoletoguttatus misidentified as Agrilaxia), but distinguished by morphological details of and genitalia

More Details

Taxonomic challenges

The hyperdiversity of Agrilus has created a taxonomic quagmire with limits difficult to define. Fisher's 1928 revision of North American species remains the only comprehensive resource but is woefully outdated. Many species are hardly distinguishable except by examination of male genitalia, and numerous new species continue to be described, particularly from underexplored regions like Mexico.

Collection methodology

are most effectively collected by beating foliage of suspected plants, rearing from infested wood, or recovering from Cerceris fumipennis nests. Some are exceptionally rarely encountered due to specific host associations and cryptic habits; A. fuscipennis was collected only three times in 25+ years despite common host plant availability.