Cluster Fly vs St Mark's Fly
Side-by-side species comparison
| Attribute | Cluster Fly | St Mark's Fly |
|---|---|---|
| Scientific Name | Pollenia rudis | Bibio johannis |
| Order | Diptera | Diptera |
| Family | Calliphoridae | Bibionidae |
| Size | 8-10 mm | 6-10mm |
| Habitat | Gardens | Underground |
| Diet | Parasites | Root Feeders |
| Regions | Europe, North America | Europe |
| Conservation | Least Concern | Least Concern |
Cluster Fly
A medium-sized, dark gray fly with golden-brown hairs on the thorax. In autumn, it gathers in large clusters inside buildings to hibernate, sometimes in the thousands.
Did You Know?
The larvae of this fly are earthworm parasites, burrowing into the worm through its skin and consuming it alive from the inside over several weeks.
St Mark's Fly
A small black fly that swarms in May. Males have large heads with huge eyes that almost meet on top.
Did You Know?
Often confused with the larger Bibio marci but emerges slightly later and has entirely dark legs.