Ashworth’s rustic  (Xestia ashworthii)

Classified as Nationally Scarce in Britain (4).

Adult Ashworth’s Rustic moths have blue-grey forewings with variable blackish flecking. The hindwings are pale and silky in appearance (2). The caterpillar grows up to 40 mm in length. When fully grown, it has a bright reddish brown head and a dark grey body that may have a green or purplish tinge in some individuals. A double row of black dashes passes along the back (3). Younger caterpillars are mainly green (5).

In Britain, this moth is found only in mountainous parts of north-west Wales (3), where it has a wide distribution (4). It is locally common in some areas, including Caernarvonshire, Merionethshire and Denbighshire (2). It extends throughout Europe from Scandinavia to Turkey and the Caucasus, Russia (4), but is very localised (5).

You can view distribution information for this species at the National Biodiversity Network Gateway.

Typically inhabits south-facing slopes on slate and limestone grasslands (4).

Adults of this single-brooded moth are present from mid-June to August and are attracted to light (2).The eggs are laid in July on the foodplants, which include common rock-rose (Helianthemum nummularium), wild thyme (Thymus serpyllum), harebell (Campanula rotundifolium), and a range of other plants. The young caterpillars feed for a period before going into hibernation. They emerge the following spring and begin to feed again. They are active during the day, and also at night if the weather is warm enough. Pupation takes place in May, either in the soil or beneath moss. The adult moths emerge from the pupa in June or July (3).

It is believed that over-grazing by sheep is the main threat affecting this moth (4).

Ashworth’s Rustic is a priority species under the UK Biodiversity Action Plan. The Species Action Plan aims to maintain the current range of this moth. Some of the sites supporting this species are nature reserves or Sites of Special Scientific Interest (SSSIs), and so the species receives a level of protection in these areas. Regular monitoring is required to accurately determine and keep track of the status and range of the species (3).

The UK Biodiversity Action Plan for this species is available at UK BAP.

View information on this species at the UNEP World Conservation Monitoring Centre.

There may be further information about this species available via the National Biodiversity Network Gateway.

To learn more about butterfly and moths conservation visit:

• Butterfly Conservation:
  www.butterfly-conservation.org