The Essex Skipper (Thymelicus lineola) is a butterfly of the Hesperiidae family.
With a wingspan of 2.5 to 2.9 cm it is very similar in appearance to the Small Skipper Thymelicus sylvestris. The easiest way to tell the difference between the two is to look at the tips of the antennae. The Essex skippers 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 and to several northern US states.
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.