Small Tortoiseshell
Aglais urticae
Tap image to enlarge · Wikimedia Commons
Overview
The Small Tortoiseshell is one of Britain's most familiar butterflies — or was. It has declined significantly in recent decades (thought to be linked to a parasitic fly introduced from the continent) and is now amber-listed. On the Sefton Coast it's still regular but less numerous than in the 1980s. Adults hibernate from August and can appear on warm winter days. The vivid orange, black and blue wing pattern is unmistakeable. Stinging Nettle beds are essential for breeding.
At a Glance
| Order | Lepidoptera |
| Family | Nymphalidae |
| Habitat | Dune grassland · Garden · Scrub edge · Open land near nettles |
| Diet | Adults: Buddleia, Aster, Sedum, thistles. Larvae: Stinging Nettle exclusively. |
| UK population | Widespread but declining; amber-listed due to long-term population fall |
| Sefton Coast | Regular throughout the Sefton Coast; less abundant than formerly but still present |
| Conservation | UK Amber List |
Where to See It
Anywhere on the Sefton Coast in warm weather — a generalist of dune grassland, gardens and scrub.
Identification
Medium butterfly. Vivid orange with black and yellow forewing base, blue-spotted black border. Similar to Large Tortoiseshell (now extinct in UK) but much smaller and more common.
Viewing & Photography Tips
Watch any Buddleia or thistle patch in summer. In early spring, hibernating adults emerge to feed before nettles are available.
Conservation Status
UK Amber List
This species is of moderate conservation concern. Population monitoring and habitat management on the Sefton Coast support its continued recovery.
Frequently Asked Questions
Why has the Small Tortoiseshell declined so much?
The decline of Small Tortoiseshell is thought to be partly caused by a parasitic fly, Sturmia bella, which arrived in Britain from the continent in the 1990s. This fly lays eggs near nettle patches; larvae burrow into caterpillars and consume them from within. Other factors include loss of nectar-rich flower habitats and changes in agricultural practice affecting nettle quality.
Related Species
Plan your visit to the Sefton Coast
Marshside RSPB, Formby pinewoods, Ainsdale NNR — practical guides to getting there, what to bring, and the best spots for each season.