Bug FAQSombre Goldenring
Thecagaster bidentata · Order: Odonata · Family: Cordulegastridae
The Sombre Goldenring dragonfly is about 8 cm long with a 10 cm wingspan and has a black body marked with yellow rings. It lives around mountain springs in Central and Southern Europe, breeding in May to June and its larvae develop for three to five years, sometimes hunting on land at night.
Source: Wikipedia
How to recognize it
Adults have a black body with distinctive yellow rings. They look similar to the related dragonfly Cordulegaster boltonii.
Source: Wikipedia
Size
Adults are about 8 cm (3.1 in) long and have a wingspan of roughly 10 cm (3.9 in).
Source: Wikipedia
Where it lives
They are found mainly around mountain springs. Larvae may leave the water at night to hunt small arthropods on the ground.
Source: Wikipedia
What it eats
Larvae live on the bottom of streams, feeding in the lowest water layers. They sometimes emerge from the water to hunt small ground arthropods at night.
Source: Wikipedia
Life cycle
Larval development lasts three to five years and can be slowed if the water freezes.
Source: Wikipedia
When you see it
Breeding occurs in May and June.
Source: Wikipedia
Where it comes from
The species occurs in Central and Southern Europe, reaching as far south as Sicily.
Source: Wikipedia
Lookalikes
It can be confused with Cordulegaster boltonii, which has a similar appearance.
Source: Wikipedia
More photos
Questions people ask
When does the Sombre Goldenring breed?
Breeding happens in May and June, with eggs deposited in the upper parts of streams.
Source: Wikipedia
What do the larvae eat?
Larvae live on the stream bottom and feed there, but they may also leave the water at night to hunt small arthropods on land.
Source: Wikipedia
Where can I find this dragonfly?
It is most common around mountain springs in Central and Southern Europe, extending south to Sicily.
Source: Wikipedia
How can I tell it apart from similar species?
Look for the black body with yellow rings; although it resembles Cordulegaster boltonii, the ring pattern is distinctive.
Source: Wikipedia
Same family (Cordulegastridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Thecagaster_bidentata
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 2026-10-24.