Moths and butterflies
Moths and butterflies make up the Lepidoptera - the Family of insects which is best studied in Orkney. After pioneering work in the 19th Century, RI Lorimer published the Lepidoptera of the Orkney Islands in 1983. Sydney Gauld now coordinates recording of moths and butterflies in the islands, with the County list standing at around 600 species.
Of the butterflies, meadow brown, small tortoiseshell and green-veined white are the most widely encountered resident species, with red admiral and painted lady being migrant visitors which can occur quite commonly. The common blue is a beautiful species which can be found in dry sunny areas where its foodplant - bird's-foot-trefoil - grows in short turf.
The large heath butterfly is typical of undisturbed areas of peaty moorland in Orkney, where its caterpillars feed on cotton-grass. This species is common locally especially on Hoy. However, the large heath is a Priority Species in the UK Biodiversity Action Plan, as numbers have declined over England and Wales due to the loss of its habitats. In Orkney, drainage and reseeding of moorland has affected the species in places, especially in the Mainland, but it has strongholds in Hoy. The subspecies of large heath found in Orkney is Ceononympha tullia scotica which has almost unspotted underwings. This lack of any striking markings makes Orkney's large heaths very easy to overlook.
The dark green fritillary is another declining butterfly species. In Orkney, sand dunes on Burray are now the main site for this beautiful intricately patterned orange butterfly - and the most northerly site in Britain for the species. Its caterpillars feed on violet leaves.
Moth species greatly outnumber butterflies, and Orkney is no exception in this respect. Only 14 butterfly species have ever been recorded here, in contrast to hundreds of moth species. Some are very widespread, but many are specific to individual habitats or locations where their foodplants grow. Sand dunes have a very particular moth fauna, as do mountain and moorland.
The hills and moors of Hoy is the only place in Orkney where northern eggar moths and yellow-ringed carpet have been recorded. Other moorland species such as emperor moth and grey mountain-carpet are much more widespread around the islands.