Lulworth skipper  (Thymelicus acteon)

The Lulworth skipper is one of our smallest butterflies (3). Males are orange-brown with light spots and a black band on the forewings. Females are darker in colour than males and do not have this dark band. The underside of both sexes is orange-brown with no markings or spots (1). The caterpillar reaches 2.4 cm in length, has a green body with a darker green, yellow-bordered line along the back and pale yellow lines along the sides (2).

Found in some areas of south and central Europe, Asia Minor and North Africa. In Britain the Lulworth skipper is largely restricted to coastal areas of south Dorset, centred on the village of Lulworth, colonies are also known from the Isle of Portland and west Dorset (3).

This skipper inhabits sheltered or south-facing slopes in unimproved calcareous grasslands, such as chalk downland and coastal grasslands (3). Tall clumps of the sole foodplant tor-grass (Brachypodium pinnatum) are required (3).

This species is single-brooded; adults fly between late June and late September, and eggs are laid in small groups in flower sheaths of tall patches of tor-grass. After hatching 3 weeks later, the larvae spin a cocoon in which to hibernate. They emerge the following spring and create tubes in which to live by spinning the leaf together. Pupation occurs amongst the clumps of tor-grass (2).

The Lulworth skipper was once found in Devon. Apart from the loss of the species in this area, its range has stayed relatively stable. Its habitats in Britain have not been destroyed, largely because the slopes on which the species occurs are too steep to be ploughed or occur in military training areas. During the twentieth century, the levels of grazing in areas inhabited by this skipper have decreased; the foodplant has been able to grow to the taller heights that suit this species as a result. Small declines in the Lulworth skipper have occurred in some areas due to an increase in grazing (4).

Scrub removal has benefited the species in some localities, and many sites are ungrazed (4). However, research has indicated that some grazing may actually benefit this butterfly, as nectar-source flowers will be encouraged, but grazing in spring and summer when the larvae tend to be located at high points on vegetation is detrimental. Maintaining the longer sward needed by this species conflicts with conservation management for other butterfly species such as the Adonis blue butterfly (Lysandra bellargus); conservation measures will therefore need to manage different parts of an area for different species, with the Lulworth skipper becoming a priority in the existing key areas (3).

For more information on this species see Butterfly Conservation's Species Action Plan:
http://www.butterfly-conservation.org/species/action_plans/lulworth_skipper/index.shtml
For more on UK butterflies and their conservation see Butterfly Conservation,
http://www.butterfly-conservation.org/
and The Millennium Atlas of Butterflies in Britain and Ireland. Asher, Warren, Fox, Harding, Jeffcoate, and Jeffcoate. (2001). Oxford University Press, Oxford

Information authenticated by Butterfly Conservation:
http://www.butterfly-conservation.org/