Head to head
Green Drake Mayfly vs Stonefly
Green Drake Mayfly
VS Stonefly
The green drake mayfly and the stonefly are two groups of aquatic insects that biologists use as indicators of clean rivers, and fly fishers know both well.
| Green Drake Mayfly | Stonefly | |
|---|---|---|
| Scientific name | Ephemera danica | Plecoptera (the stonefly order) |
| Group | A mayfly, whose adults emerge in a mass hatch | A stonefly, an ancient order of winged insects |
| Nymph habitat | Burrows into fine gravel and silt in rivers and lakes, with strong digging legs and feathery gills | Clings to the underside of submerged rocks in cold, clean, well-oxygenated, fast-flowing water |
| Time as a nymph | One or two years underwater | Varies by species, with some grazing algae and others hunting smaller invertebrates |
| Emergence | Hatches in huge numbers in late spring, particularly in May and June, first as a dull dun and then a shinier spinner | Nymphs climb out of the water onto a rock, log, or streamside plant before splitting their skin, and some species emerge in mid-winter |
| Adult life | Has no functional mouth and lives only a day or two, long enough to mate and lay eggs | Generally weak, fluttering fliers that stay close to the stream and typically eat little or nothing |
| Pollution | Widespread in clean rivers and lakes, but sensitive to pollution and silting | Among the most pollution-intolerant of all common freshwater invertebrates, so its presence signals clean water |
| Conservation status | Not Evaluated, but widespread across Europe | Least Concern, in cold, clean streams worldwide except Antarctica |
Green Drake Mayfly vs Stonefly: common questions
Which one lives in silt?
The green drake mayfly, whose nymph burrows into fine gravel and silt in rivers and lakes.
Which one is more sensitive to pollution?
The stonefly, whose nymphs are among the most pollution-intolerant of all common freshwater invertebrates.
What is the EPT group?
It is the group of mayflies, stoneflies, and caddisflies, whose diversity in a stream sample is used as a simple measure of water quality.