Agrilus bilineatus

Adults are metallic beetles with two pale longitudinal stripes running the length of the dark elytra, giving the species its common name. The overall body is somewhat flattened and elongated, typical of the genus. Larvae are white, legless, and C-shaped with enlarged thoracic segments, creating winding galleries in the phloem and outer sapwood that are visible beneath the bark. The species can be distinguished from other Agrilus by its host association with oaks and chestnuts combined with the distinctive paired elytral stripes.

Oak-dominated forests and woodlands; primarily attacks stressed or weakened trees, particularly those on dry sites, suffering from drought, defoliation, or other physiological stress. The beetle colonizes the trunks and main branches of living host trees rather than dead twigs.

Native to eastern North America; present throughout the eastern deciduous forest region from Canada (Manitoba, New Brunswick) through the United States. Introduced and established in Turkey, representing a significant range expansion into Europe.

Adults present from early June through mid-September, with peak flight and oviposition occurring during the second half of June in northern populations. Emergence patterns are temperature-dependent.

Larvae feed on phloem and outer sapwood of oak trees (Quercus spp.) and chestnut (Castanea spp.), creating galleries that girdle the conducting tissues. Adults consume oak foliage, showing significant preference for oak over other hardwood foliage.

• Quercus spp. - primary larval hostoaks, both red and white oak groups
• Castanea spp. - larval hostchestnut species
• Quercus velutina - documented hostblack oak
• Quercus alba - documented hostwhite oak

Univoltine (one-year life cycle). Females lay eggs in bark crevices. Larvae pass through four instars, tunneling through phloem and outer sapwood; third and fourth instars cause the most damage by girdling xylem and phloem. Fourth instar larvae overwinter in pupal cells located in outer bark or sapwood when bark is thin. Pupation occurs in spring. Adults emerge June-September. Tree death normally occurs after 2-3 years of infestation, though may happen in a single season with heavy attack.

Strongly attracted to stressed host trees, detecting them within hours of stress onset through olfactory response to tree-released volatiles including ethanol and oak-specific compounds. Initial attack typically begins in the live crown and proceeds downward in successive years without reinfestation of previously killed areas. Adults show marked preference for red oak group species over white oak group. Stressed trees with poor or fair crown condition are colonized preferentially over healthy trees.

Secondary pest that contributes to oak decline and mortality, particularly following environmental stress events such as drought or defoliation. Acts as a primary mortality agent during outbreak conditions. Facilitates entry of decay fungi and accelerates decomposition of weakened trees. Populations increase following gypsy moth defoliation events, with beetle abundance positively associated with prior year tree mortality.

Significant forest pest causing economic damage to oak timber resources and ornamental trees. Tree mortality impacts forest composition and ecosystem services. Recently established in Turkey, creating concern for European forestry. Potential biological control agent Phasgonophora sulcata (a native parasitoid) has been identified but is not species-specific.

• Agrilus anxiusBoth are trunk borers of living trees in the genus Agrilus; bronze birch borer attacks Betula rather than Quercus/Castanea
• Agrilus planipennisBoth are economically important trunk borers of living trees; emerald ash borer attacks Fraxinus and has more uniformly metallic green coloration without paired stripes
• Other Agrilus speciesMost other Agrilus develop in dead twigs and branches rather than living tree trunks, and lack the distinctive paired elytral stripes

• forest pest
• oak mortality
• invasive species
• jewel beetle
• secondary pest
• univoltine
• phloem feeder
• Turkey introduction

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Two new species of Agrilus from Mexico | 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
• Online Entomology Outreach: Tips From a Long-Running Program
• Two-lined Chestnut Borer, Agrilus bilineatus (Weber)
• Biology of Two-Lined Chestnut Borer, Agrilus bilineatus, in Pennsylvania and New York1
• Colonization by Armillaria mellea and Agrilus bilineatus of Oaks Injected with Ethanol
• Dynamics of twolined chestnut borer Agrilus bilineatus as influenced by defoliation and selection thinning
• THE BIOLOGY AND ECOLOGY OF THE TWOLINED CHESTNUT BORER, AGRILUS BILINEATUS (COLEOPTERA: BUPRESTIDAE), ON OAKS, QUERCUS SPP., IN WISCONSIN
• The role of host tree condition in attack of white oaks by the twolined chestnut borer, Agrilus bilineatus (Weber) (Coleoptera: Buprestidae)
• ATTRACTION OF THE TWOLINED CHESTNUT BORER,AGRILUS BILINEATUS(WEBER) (COLEOPTERA: BUPRESTIDAE), AND ASSOCIATED BORERS TO VOLATILES OF STRESSED WHITE OAK
• Buprestidae, Cerambycidae, and Scolytidae Associated with Successive Stages of <i>Agrilus Bilineatus</i> (Coleoptera: Buprestidae) Infestation of Oaks in Wisconsin
• Observations of the Biology of <i>Phasgonophora Sulcata</i> (Hymenoptera: Chalcididae), a Larval Parasitoid of the Twolined Chestnut Borer, <i>Agrilus Bilineatus</i> (Coleoptera: Buprestidae), in Wisconsin