False Stable Fly vs St Mark's Fly

Side-by-side species comparison

Attribute False Stable Fly St Mark's Fly
Scientific Name Muscina stabulans Bibio johannis
Order Diptera Diptera
Family Muscidae Bibionidae
Size 7-10 mm 6-10mm
Habitat Farmland Underground
Diet Predators Root Feeders
Regions Europe, North America, Asia Europe
Conservation Least Concern Least Concern

False Stable Fly

A robust fly resembling a large house fly with reddish-yellow patches at the wing base. Larvae can be facultative predators of other fly larvae.

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Did You Know?

Its predatory larvae sometimes consume house fly larvae, making it an accidental biocontrol agent.

St Mark's Fly

A small black fly that swarms in May. Males have large heads with huge eyes that almost meet on top.

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Did You Know?

Often confused with the larger Bibio marci but emerges slightly later and has entirely dark legs.