St Mark's Fly vs Sheep Nose Bot Fly
Side-by-side species comparison
| Attribute | St Mark's Fly | Sheep Nose Bot Fly |
|---|---|---|
| Scientific Name | Bibio johannis | Oestrus ovis |
| Order | Diptera | Diptera |
| Family | Bibionidae | Oestridae |
| Size | 6-10mm | 10-12 mm |
| Habitat | Underground | Farmland |
| Diet | Root Feeders | Parasites |
| Regions | Europe | Worldwide |
| Conservation | Least Concern | Least Concern |
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.
Sheep Nose Bot Fly
A parasitic fly that shoots live larvae into the nostrils of sheep and goats while in flight. Larvae develop inside the nasal sinuses, causing distress to livestock.
Did You Know?
This fly does not lay eggs — it shoots live first-instar larvae directly into the nostrils of sheep while flying past at speed, a method called larviposition.