Bug FAQEuropean Green Drake
Ephemera danica · Order: Ephemeroptera · Family: Ephemeridae
Also called: Black Drake, British Green Drake, Green Drake, Grey Drake
The European Green Drake is a small mayfly, 15 to 25 mm long, with three tail filaments and distinctive wing markings. Adults emerge in spring, are most common in May to June, and may be seen from April through November.
Source: Wikipedia
How to recognize it
It shows characteristic markings and has three long tail filaments (cerci).
Source: Wikipedia
Size
Males are 15 to 20 mm long, while females are larger at 16 to 25 mm.
Source: Wikipedia
What it eats
Nymphs dig tunnels in river gravel and filter organic detritus for food. Adults are prey for swallows, trout, amphibians and spiders.
Source: Wikipedia
Life cycle
The life cycle usually lasts one to two years, but nymphs can remain up to three years.
Source: Wikipedia
When you see it
Adults are most abundant in May to June, though they can be seen from April to November.
Source: Wikipedia
Where it comes from
Its range includes clear-water rivers and lakes throughout Europe, including the British Isles.
Source: Wikipedia
Lookalikes
It is the most commonly seen British member of the Ephemeridae family, so it is often the first mayfly people notice.
Source: Wikipedia
Where it is found in the US
Recorded in 1 of 51 states and DC. Most records: Louisiana.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
More photos
Questions people ask
When do European Green Drake adults appear?
Adults are mainly seen in May and June, but can be present from April through November.
Source: Wikipedia
What do the nymphs eat?
Nymphs dig tunnels in river gravel and filter organic detritus from the water.
Source: Wikipedia
Same family (Ephemeridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Ephemera_danica
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.