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.

Glöyn disylw yw Gweirlöyn Bach y Waun, nad yw’n arfer hedfan ond pan fydd yr haul yn tywynnu; anaml y bydd yn glanio’n uwch na metr uwchben y ddaear. Mae’n cadw ei adenydd ar gau bob amser pan fydd yn llonydd. Mae smotiau ar ffurf llygaid ar flaenau wyneb isaf yr adenydd blaen. Gwelir bandiau brown, llwyd a lliw hufen ar yr ôl-adenydd. Mae nifer y deoreidiau a’r cyfnodau hedfan yn amrywio, ac mae’r oedolion i’w gweld yn barhaus o ddiwedd mis Ebrill tan fis Medi ar rai safleoedd yn ne Lloegr.

Glöyn lliw oren a brown sy’n bolaheulo’n aml ar waliau, cerrig a daear galed lom.

Arferid ei weld ar hyd yr arfordiroedd cyn iddo ymledu’n ehangach yng ngogledd Lloegr a de’r Alban. Mae’n debyg o ran ei faint a’i liw i Weirlöyn y Perthi, ond mae patrymau Gweirlöyn y Cloddiau’n fwy cymhleth ac fe’i camgymerir weithiau am un o’r Brithegion bach.

Mae Britheg y Gors dan fygythiad nid yn unig yng ngwledydd Prydain ond ledled Ewrop, ac o ganlyniad mae ymdrechion aruthrol yn cael eu neilltuo ar gyfer y gwaith o’i achub.

Mae adenydd siecrog y rhywogaeth brydferth hon yn loywach eu patrymau na rhai’r brithegion eraill, a gwelir hiliau ohonynt â marciau mwy amlwg yn yr Alban ac Iwerddon. Mae’r larfâu’n gweu gweoedd tra gweladwy y gellir eu cofnodi’n hawdd tua diwedd yr haf.

Un o’n brithegion ehangaf eu hamrediad yw’r Fritheg Werdd; gellir ei gweld yn hedfan yn chwim mewn gwahanol gynefinoedd heulog agored. Mae’r gwrywod yn debyg eu golwg i’r Fritheg Frown, sy’n brinnach o lawer ond a welir weithiau’n cyd-hedfan â hwy ar lethrau rhedynog. Gellir gwahanu rhyngddynt trwy wylio’r marciau ar yr is-adenydd, a welir tra’u bod yn ymborthi ar flodau megis ysgall.

Mae niferoedd y Fritheg Werdd wedi dirywio mewn rhannau o ganolbarth a dwyrain Lloegr, ond erys yn niferus yn lleol yng ngorllewin Lloegr,  ar hyd arfordir Cymru ac yn yr Alban.

The males have triangular grey-brown forewings with dark-edged jagged crossbands which are distinctively held overlapping at rest. The females are completely wingless with a barrel-shaped body and a tuft of hairs on the end of the abdomen. The adult males flay after dark and are attracted to light.

The light green caterpillars can be found from late April to June overwintering as pupae in a fragile cocoon under the ground.

The forewings of the English subspecies are grey or greenish-white with a large pale spot near the centre of the leading edge. The Scottish subspecies is a darker grey. They fly at night and are attracted to light but might also fly during the day on sunny afternoons.

The caterpillars can be found from mid-May to mid-July feeding at night and resting between two leaves spun flat together during the day. They overwinter as pupae on the ground amongst leaf litter.

The English subspecies or is similar in appearance to the Figure of Eighty but the cross-lines are more wavy, often thicker and more numerous. The Scottish subspecies scotica is sometimes a paler grey colour or occasionally brown. The Irish subspecies hibernica varies between the two others in colour with paler markings.

The adults fly at night and are attracted to light.

Smaller than the Satin Lutestring. Can be identified by the pair of small dark spots in the centre of the forewing. The strength of the cross-lines varies considerably between forms. The darker form f. obscura is almost entirely grey-brown and is common across much of England. Draker forms are often found in London, Midlands and Scotland and forms with stronger bands are more often found in the north and west including Ireland.

The adults fly at night and are attracted to light.

Identified by three or sometimes four narrow and yellowish-white bands on the abdomen and vertical stripes on the thorax with the absence of and orange scales on the forewings.

The adults can sometimes be seen visiting flowers of Thrift and Thyme. The caterpillars feed inside the roots and stems of the foodplant from August to the following May, overwintering as part-grown larvae.

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