Green Drake
Ephemera danica
The Common Mayfly is one of Europe's largest mayfly species, known for its distinctive dark-spotted wings and three long tail filaments. The larvae are burrowers, spending two to three years in the sandy or silty substrates of clean, oxygen-rich streams before emerging as adults. The winged adults, which appear in synchronized swarms typically in late spring, do not feed and survive only for a few days to reproduce. They are highly significant in aquatic ecosystems as bioindicators and as a primary food source for various fish species.
Details
Identification
Three long tail filaments, yellowish-white abdomen with dark triangular markings, forewings much larger than hindwings, wings with dark spots.
Social behavior
Larvae live as solitary burrowers in the substrate; adults form large, coordinated swarms for mating purposes.
Diet
Larvae are detritivores, feeding on fine organic particles and algae within the sediment; adults have reduced mouthparts and do not feed.
Hunting strategy
Passive collecting and filtering of organic matter in the riverbed.
Spawning substrate
Eggs are released by females onto the water surface during flight and sink into sandy or gravelly substrates.
Overwintering
Overwintering as larvae within the aquatic sediment.
Ecology
Ecological role
Important primary consumer that processes organic matter and serves as a fundamental food source for fish, birds, and predatory insects.
Natural predators
Fish (trout, grayling), birds (dippers, swallows), predatory insects (dragonfly larvae).
Competitor species
Other burrowing mayfly larvae such as Ephemera vulgata.
Ecosystem service
Nutrient cycling in aquatic systems, pollination (minor), basis for ecotourism (fly fishing).
Threats
Water pollution, eutrophication, river engineering, pesticide use in agriculture, and light pollution.
Scientific profile
Profile
Distinguishing features
Possesses three very long tail filaments (cerci). Wings are held upright at rest. Characterized by dark triangular markings on abdominal segments 7 to 9, which distinguishes it from Ephemera vulgata (where markings occur on almost all segments). Large body size.
Role in food web
Central role as food for fish (especially trout), birds (sand martins), and bats. Important processor of organic matter.
Protection & threats
Main threats
Water pollution, eutrophication, clogging of the interstitial zone by fine sediments (siltation), pesticide runoff from agriculture, river engineering.
Population trend
Widespread and often common in Central Europe, but locally declining due to habitat degradation.
Conservation measures
Preservation and restoration of natural river dynamics, reduction of nutrient and fine sediment input, protection of riparian buffer zones.