Photo: Bien-Zenker GmbH / CC BY-SA 4.0
Osmia bicolor
Red-tailed Mason Bee
A striking mason bee (9–12 mm) with a black head and thorax and a bright orange-red hairy abdomen. It is famous for nesting in empty snail shells, covering them with pine needles or grass for camouflage. It is one of the earliest bees to emerge in spring, flying from April to July. In Switzerland it occurs in dry, sunny habitats such as calcareous grasslands, rocky slopes, and warm forest edges, widespread from lowlands to montane elevations. Swiss Red List: Least Concern (LC).
Species Facts
- Size
- 9–12 mm
- Flight Period
- April to July
- Nesting
- Cavities
- Specialization
- Generalist
- Abundance
- Uncommon
- Family
- Megachilidae
External Sources
This data has been cross-referenced with national sources:
Data Source & Copyright
| Category | Source / Author | License |
|---|---|---|
| Photo | Bien-Zenker GmbH | CC BY-SA 4.0 |
| Taxonomy & Distribution | InfoFauna Switzerland | Public data |
| Global Distribution | GBIF | CC BY 4.0 |
Data Quality
High Quality Last audit: 2026-05-22
Completeness: 100%
✓Photo exists✓Traits consistent✓Description quality✓Red List referenced✓Attribution verified
Confidence: 67%
IdentifiabilityMediumImage confidenceMediumImage qualityHighTrait coherenceHigh
