Mae’n hawdd peidio â gweld ein glöyn byw brodorol lleiaf i gyd, yn rhannol oherwydd ei faint a’i liw tywyll, ond yn rhannol hefyd oherwydd na ddeuwn o hyd iddo’n aml ond ar glytiau bach o laswelltir cysgodol lle mae ei unig blanhigyn bwyd, sef Meillion Melyn (Bysedd Mair), i’w weld yn tyfu.

Not found in the UK.

Size and Family

  • Family: Blues
  • Size: Small / Medium
  • Wing Span Range (male to female): 30-36mm

Conservation Status

  • Butterfly Conservation priority: Low                    
  • European Status: Vulnerable

Caterpillar Foodplants

Caterpillars feed on Marsh Gentian (Gentiana pneumonanthe)


Damp meadows below 1000m

Not found in the UK.

Overwinters as a caterpillar.

Size and Family

  • Family: Blues & Hairstreaks
  • Size: Small
  • Wing Span Range (male to female): 20-30mm

Conservation Status

  • Butterfly Conservation priority: Low                    
  • European Status: Not threatened

Caterpillar Foodplants

Caterpillars feed on Common Bird's-foot-trefoil and Gorse.


Grassy, flowery places such as Meadows, farmland and wasteland.

Not found in the UK. There are two forms of this magnificent butterfly - the blue form ilia and the orange-brown form clytie, the latter is more commonly encountered in southern regions of its distribution.

This is a large and distinctive butterfly, even in flight, as the white wing borders are unmistakable. The adults live solitary and, as such, migrate singly rather than in the swarms associated with other migrant species.

Sometimes referred to as the Blue Underwing, the Clifden Nonpareil is a very large and impressively beautiful and rare moth.

This unmistakable insect is strongly attracted to sugar at dusk and will come to light but can also be seen by day at rest on tree trunks and walls. It has even been recorded flying inland from the sea.

Winter is spent as an egg on the foodplant with the caterpillars hatching the following spring when they can be found through to July, feeding at night. The pupa is made in a silken cocoon that is spun between leaves or among leaf litter.

The Large Tortoiseshell was once widespread across Britain and most common in the woodlands of central and southern England but while its numbers were always known to fluctuate, it declined to extinction by the 1960s. This butterfly has not been recorded from Ireland.

It is still common in some parts of Europe, but declining in others. There continue to be sporadic records in Britain, the majority from the south coast but some are considered to be of specimens released from reared stock rather than genuine immigrants.

The Long-tailed Blue is an exotic migrant from the Mediterranean with a handful typically reaching UK shores each year, but experts believe climate change is behind this butterfly reaching our shores more regularly and in vastly increased numbers.

One of the largest migrations took place in 2015 when 60 adult butterflies crossed the Channel in August and laid 1000s of eggs in gardens and allotments along the South Coast.

A large, strong-flying butterfly restricted to the Norfolk Broads, although migrants are occasionally seen elsewhere. Pale yellow wings with black veins and blue margins.

This is one of our rarest and most spectacular butterflies. The British race britannicus is a specialist of wet fenland and is currently restricted to the Norfolk Broads. Here the adults can be seen flying powerfully over open fen vegetation, stopping to feed on flowers such as thistles and Ragged-Robin.

The adults come to light, but do not feed. 

They overwinter as shiny black/brown pupae, below or near the larval foodplant. The caterpillars can be seen from June to September and resemble the Poplar Hawk-moth caterpillar, apart from the bluish-coloured spike at the rear.

Flight Season

Flies from May to July in one generation.

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