The Essex Skipper (Thymelicus lineola) is a butterfly of the Hesperiidae family. In North America, it is known as the European Skipper.

Thymelicus lineola showing black underside to antennae tips

With a wingspan of 2.5 to 2.9 cm it is very similar in appearance to the Small Skipper Thymelicus sylvestris. They can be told apart by the undersides of the tips of the antennae: the Essex skipper's are black whereas those of the Small Skipper are orange. This butterfly occurs throughout much of the Palaearctic region. Its range spreads from southern Scandinavia through Europe to North Africa and east to Central Asia It was only identified in the UK in 1889 and its range is expanding both in England and in northern Europe. In North America, this butterfly was accidentally introduced in 1910 via London, Ontario and has spread across southern Canada^[1] and to several northern US states.^[2]

Life cycle

Eggs are laid in strings on the stems of grasses where they remain over the winter. The favoured foodplant is Cock's-foot (Dactylis glomerata) and it rarely uses the Small Skipper's favoured foodplant Yorkshire Fog. Other choices include Creeping Soft Grass (Holcus mollis), Couch Grass (Elymus repens), Timothy-grass (Phleum pratense), Meadow Foxtail (Alopecurus pratensis), False Brome (Brachypodium sylvaticum) and Tor-grass (Brachypodium pinnatum). The caterpillars emerge in the spring and feed until June before forming shelters from leaves tied with silk at the base of the foodplant to pupate. The adult flies from July to August. Like most skippers, they are fairly strictly diurnal, though individuals are very rarely encountered during the night.^[3]

The egg is pale greenish-yellow, oval in shape, flattened above and below ; the top is slightly depressed.The caterpillar is green, with the incisions between the rings yellowish ; there is a darker green stripe on the back, and the lines on the sides are yellow. The head is pale brown and striped with darker brown. The chrysalis is long, yellowish-green in colour, and retains the dark dorsal stripe seen in the caterpillar.

References

• Asher, Jim et al.: The Millennium Atlas of Butterflies of Britain and Ireland Oxford University Press