Tracheini

Pronunciation

How to pronounce Tracheini: /ˈtræk.i.ˌi.naɪ/

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Summary

Agrilus biguttatus, known as the two-spotted oak borer, is a buprestid beetle detrimental to oak trees, particularly during periods of tree stress such as drought. Its life cycle and feeding behavior contribute significantly to oak decline in Europe and pose a potential risk if introduced to new ecosystems.

Physical Characteristics

Adult beetle 8 to 13 mm long, metallic green with black or yellow cast; a pair of white spots on the inner edges of the elytra. Larvae creamy white, up to 43 mm long, legless with a pair of horns on the last abdominal segment.

Identification Tips

Look for D-shaped exit holes on oak trees and damaged bark; adults are distinguished by their metallic sheen and size.

Habitat

Inhabits deserts, xeric shrublands, Mediterranean scrub, mixed forests, and temperate coniferous forests. Prefers old oak trees with specific sizes and health conditions for optimal larval development.

Distribution

Widespread throughout Europe, northern borders of southern Sweden, the UK, North Africa, and Northern Asia. Expanding its range in northern Europe due to climate changes.

Diet

Larvae feed on the inner bark and vascular tissues of oak trees and, to a lesser extent, European beech and chestnut.

Life Cycle

The beetles mature through several life stages: egg, larva, pupa, and adult. The complete life cycle can take one to two years depending on environmental conditions.

Reproduction

Females lay eggs within cracks on the bark of suitable oak trees after mating; eggs are laid in clusters, typically on south-facing sides of the trees.

Predators

Woodpeckers, European red-bellied clerid (Thanasimus formicarius), wasps from the family Ichneumonidae such as Dolichomitus imperator.

Ecosystem Role

Plays a role in oak decline, significantly affecting the health of oak trees and influencing forest ecosystems.

Economic Impact

Considered a pest affecting oak trees, contributing to oak decline which has significant ecological and economic implications.

Evolution

Part of a diverse lineage within the subfamily Agrilinae, which has undergone significant evolution with both wood-boring and leaf-feeding habits.

Misconceptions

Often mistaken for other buprestid beetles, and its role in oak decline may be understated or misunderstood as solely caused by other factors.

Tags

• Agrilus
• beetle
• oak decline
• invasive species
• pest management