Last week I spent Tuesday to Friday walking about 65 miles along the Dorset coast path by myself – an exhausting but interesting journey on which I saw lots of great wildlife. As I walked along the section of cliffs from Durlston head (near Swanage) to Lulworth Cove I came across quite a few small, brown fluttering insects. They were butterflies, though they looked more like moths, called Skippers (a lovely name) and by the darkness of the wings, the colour of the antennae and the semi-circle of golden marks on the forewing I could tell they were Lulworth Skippers. This was a new species for me and one which I was hoping to see on this walk as it has a greatly restricted distribution.
- The Lulworth Skipper (Thymelicus acteon) is one of Britain’s smallest butterflies with a wingspan of just 2.5cm, it is also the smallest species in its genus. Its darkness of colour and amber ‘sun-ray’ marks on the wings separate it from other Skippers – males are almost an olive-brown shade.
- Its global distribution includes North Africa and much of central Europe but in the UK it is restricted solely to the stretch of Dorset coast between Burton Bradstock and Swanage, its name reflects this as well as Lulworth being the place that this species was first collected in Britain in 1832 by James Dale.
- Due to its small range it is a UK Biodiversity Action Plan priority species – although the population has been stable for decades and seems healthy. On the continent it has undergone declines and thus has a status of ‘Vulnerable’.
- The caterpillar food-plant is tall stands of Tor-grass found in the species’ habitat of calcareous grassland on chalk or limestone, in its UK range it prefers grassland on south-facing slopes and out of strong winds, such as in sheltered coastal valleys.
- The Lulworth Skipper is the only British butterfly that has never had any other vernacular name suggested for it.
- The species is sexually dimorphic in that the female not only differs in appearance from the male (with a lighter colour and the ‘sun-ray’ markings) but is also slightly larger – this is in contrast with other UK Skippers that have very similar sexes.
- This Skipper requires long grass as its breeding habitat so it has benefited from reduced grazing as sheep farming has declined in the area and rabbits have dropped off from myxomatosis.
- The Lulworth Skipper, along with all Skippers, is placed in the family Hesperiidae; separate from all other butterflies a they are morphologically distinct. Some scientists have suggested that as Skippers exhibit features of both butterflies and moths that they are the most ancient, basal branch of the Lepidoptera tree from which modern moths and butterflies diverged.