Yorkshire's latitude places it at the northern edge of the ranges of several butterfly species whose populations have waxed and waned over the last two centuries for which we have sufficient extant records. Since the 1990s butterflies once consideredrare or absent in Yorkshire, such as Comma Polygonia c-album, Speckled Wood Pararge aegeria, Gatekeeper Pyronia tithonus and Holly Blue Celastrina argiolus have expanded northwards to become commonplace (Asher et al., 2001; Fox et al., 2007). There has even been the arrival of Essex Skipper Thymelicus lineola, a butterfly whose northern range has historically always been to the south of Yorkshire. It is not always clear what mechanisms drive expansion and restriction in range but clearly sustained increases in global mean temperature from the early twentieth century onwards (Stott et al., 2000; IPCC, 2013) has been a major factor (Asher et al., loc. cit; Parmesan et al., 1999). This article aims to review how the Speckled Wood, Comma, Gatekeeper, HollyBlue and Essex Skipper have fared in Yorkshire by comparing the status of these butterflies in the period2004-2017 against the previous period of 1995-2003. The analysis will provide an update to Frost (2005) on how these recent lepidopteral colonisers of Yorkshire have fared.
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