St Mark's Fly vs Black Horse Fly
Side-by-side species comparison
| Attribute | St Mark's Fly | Black Horse Fly |
|---|---|---|
| Scientific Name | Bibio johannis | Tabanus atratus |
| Order | Diptera | Diptera |
| Family | Bibionidae | Tabanidae |
| Size | 6-10mm | 20-28 mm |
| Habitat | Underground | Farmland |
| Diet | Root Feeders | Blood Feeders |
| Regions | Europe | Eastern United States from the Great Plains to the Atlantic coast |
| 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.
Black Horse Fly
A very large entirely black horse fly and one of the biggest flies in North America. Females are persistent blood-feeders that can harass livestock and humans during summer months.
Did You Know?
Its larvae are aquatic predators that live in muddy pond bottoms and can take up to two years to complete development.