Black Mayfly vs March Brown Mayfly

Side-by-side species comparison

Attribute Black Mayfly March Brown Mayfly
Scientific Name Ephemera danica var. nigra Rhithrogena germanica
Order Ephemeroptera Ephemeroptera
Family Ephemeridae Heptageniidae
Size 15-25 mm body 10-14 mm
Habitat Rivers & Streams Rivers & Streams
Diet Omnivores Omnivores
Regions Europe Europe
Conservation Least Concern Near Threatened

Black Mayfly

A dark color variant of the common Green Drake mayfly found in some European populations. The dark form is more prevalent in upland, acidic waters. Important for trout feeding.

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Did You Know?

The dark form predominates in acidic upland streams while the typical yellow form prefers alkaline lowland rivers.

March Brown Mayfly

A spring-emerging mayfly with a brownish body and two tails, historically important to European fly fishing. Its flat nymphs cling to rocks in fast water.

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Did You Know?

This species has declined significantly in many European rivers due to pollution and is now considered an indicator of water quality.