Callicera

Distinguished from other hoverfly genera by the combination of: (1) extremely long antennae with elongated scape and pedicel, (2) metallic body coloration, (3) bumblebee-mimicking robust build, and (4) wing venation characteristic of Eristalinae. Similar metallic syrphids (e.g., some Cheilosia, Ferdinandea) lack the exaggerated antennal length.

Medium-sized to large hoverflies with wing length 9.75–15 mm. Body metallic, often with green, blue, or coppery reflections. Antennae exceptionally long, extending well beyond head. Overall form mimics bumblebees (Bombus).

Associated with overmature trees containing moist rot-holes. Adults frequent woodland and forest edge habitats. Presence indicates long-established woodland with standing dead wood and tree cavities.

Holarctic distribution. Records confirmed from Denmark (DK), Norway (NO), and Sweden (SE). Broader range includes Palearctic and Nearctic regions.

Larval stage develops in moist rot-holes of overmature trees, feeding as saprophages on decaying organic matter. Adult emergence and activity period not specified in available sources.

Larvae contribute to nutrient cycling in decaying wood microhabitats. Adults may participate in pollination. All species considered rare; presence indicates high-quality old-growth forest ecosystems.

Used as bioindicators for conservation assessment of ancient woodland and old-growth forest habitats. Rarity makes them of conservation interest.

• FerdinandeaAlso metallic Eristalinae with robust build, but antennae much shorter and body form less distinctly bumblebee-like.
• CheilosiaSome species metallic, but generally smaller with short antennae and different wing venation.

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• Catalogue of Life
• Meloidae Holdings | Entomology Research Museum