Phloeotribini

Distinguished from other Scolytinae tribes by the obliquely truncate, three-segmented antennal club. The posterior margin of the pronotum is elevated or bears a carina, separating Phloeotribini from the closely related Corthylini. The exposed abdominal tergites and small size help distinguish them from larger bark beetle tribes such as Scolytini. Examination of antennal club structure requires magnification.

Small bark beetles, usually 1.5–3 mm in length. Body cylindrical and compact, typical of Scolytinae. Antennal club with three distinct segments, appearing obliquely truncate. Pronotum with a distinctive posterior margin that is often elevated or carinate. Elytra short, exposing one or two abdominal tergites. Coloration generally dark brown to black.

Associated with dead, dying, or stressed woody branches and twigs of broadleaf trees and shrubs. Often found in recently dead material 1–5 cm in diameter. Habitats include forest edges, woodlots, orchards, and urban areas where host trees are present. Not known to colonize healthy, vigorous trees.

Widespread in the Holarctic region, with highest diversity in North America and Eurasia. Present in temperate and subtropical regions; records extend into Central America and parts of Asia. Absent from Australia and most of Africa.

Adult activity peaks in spring and early summer, with some species showing a secondary peak in late summer. Timing varies with latitude and local climate. Overwintering occurs primarily as adults in bark crevices or leaf litter.

• Quercus - breedingdead branches
• Carya - breedingdead branches
• Castanea - breedingdead branches
• Prunus - breedingdead branches and twigs

Development occurs in maternal galleries constructed in phloem of dead branches. Larvae feed on symbiotic fungi and phloem tissue, creating irregular feeding niches. Pupation occurs in chambers within the bark. Generation time varies from one to multiple generations per year depending on species and climate. Adults emerge through exit holes and may disperse to new host material or overwinter.

Adults engage in gallery construction in small-diameter dead wood. Males typically initiate galleries and are joined by females. Gallery systems are relatively simple compared to ambrosia beetles, consisting primarily of longitudinal or branched maternal tunnels with larval niches. Adults are capable of flight and locate hosts through olfactory cues from stressed or dead wood.

Decomposers of dead woody material, facilitating nutrient cycling in forest ecosystems. Their activity in small branches contributes to early stages of wood decomposition. Associated fungi may play roles in cellulose breakdown. Provide food resources for predatory beetles, parasitoids, and woodpeckers.

Occasional pests in orchards and nurseries when breeding in pruned branches or stressed trees. Not considered major economic pests due to restriction to dead or dying material. Some species have been intercepted in international trade, leading to phytosanitary concerns. Historical association with chestnut blight in North America, though not a primary vector.

• CorthyliniShares small size and association with twigs/branches, but Corthylini have a rounded antennal club and lack the elevated pronotal carina of Phloeotribini.
• HypoboriniSimilar compact body form, but Hypoborini have different antennal club structure and are primarily associated with cones or seeds rather than branches.
• DryocoetiniOverlaps in size and habitat, but Dryocoetini typically have more complex gallery systems and different antennal club proportions.

Occasionally misidentified as ambrosia beetles due to small size and association with wood; however, Phloeotribini lack the specialized mycangia for fungal transport characteristic of true ambrosia beetles in Xyleborini.

• bark beetles
• Scolytinae
• dead wood insects
• forest decomposers
• twig beetles

• BugGuide