St Mark's Fly vs Latrine Fly

Side-by-side species comparison

Attribute St Mark's Fly Latrine Fly
Scientific Name Bibio johannis Fannia scalaris
Order Diptera Diptera
Family Bibionidae Fanniidae
Size 6-10mm 5-7 mm
Habitat Underground Wetlands
Diet Root Feeders Scavengers
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.

Latrine Fly

A small fly that breeds in excrement and decaying organic matter in latrines and drains. It can cause urogenital myiasis when larvae enter the urinary tract.

💡

Did You Know?

Its flattened, spiny larvae are among the few fly species documented to cause urinary myiasis in humans.