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Here are 2010's earliest sightings of resident and migrant butterflies, as reported to Butterfly Conservation.
All of the resident butterfly species have now emerged.
Last update: 23 August, 2010
| Vernacular name | Scientific name | Date | Location |
| Chequered Skipper | Carterocephalus palaemon | 20 May | Argyll |
| Small Skipper | Thymelicus sylvestris | 4 June | Dorset |
| Essex Skipper | Thymelicus lineola | 17 June | Norfolk |
| Lulworth Skipper | Thymelicus acteon | 28 May | Dorset |
| Silver-spotted Skipper | Hesperia comma | 11 July | Sussex |
| Large Skipper | Ochlodes sylvanus | 18 May | Cornwall |
| Dingy Skipper | Erynnis tages | 13 April | Sussex |
| Grizzled Skipper | Pyrgus malvae | 6 April | Sussex |
| Swallowtail | Papilio machaon | 19 May | Norfolk |
| Wood White | Leptidea sinapis | 24 April | Surrey |
| Réal's Wood White | Leptidea reali | 30 April | Co. Armagh |
| Clouded Yellow | Colias croceus | 18 April | Isle of Wight |
| Brimstone | Gonepteryx rhamni | 17 Jan | Hampshire |
| Large White | Pieris brassicae | 14 March | Isle of Wight |
| Small White | Pieris rapae | 15 March | Dorset |
| Green-veined White | Pieris napi | 15 March | Devon |
| Orange-tip | Anthocharis cardamines | 3 April | Yorkshire |
| Green Hairstreak | Callophrys rubi | 6 April | Hampshire |
| Brown Hairstreak | Thecla betulae | 24 July | Wiltshire |
| Purple Hairstreak | Neozephyrus quercus | 12 June | Isle of Wight |
| White-letter Hairstreak | Satyrium w-album | 20 June | Derbyshire |
| Black Hairstreak | Satyrium pruni | 9 June | Cambridgeshire |
| Small Copper | Lycaena phlaeas | 25 March | Norfolk |
| Small Blue | Cupido minimus | 18 April | Somerset |
| Silver-studded Blue | Plebeius argus | 1 June | Cornwall |
| Brown Argus | Plebeius agestis | 1 May | Somerset |
| Northern Brown Argus | Plebeius artaxerxes | 20 May | Cumbria |
| Common Blue | Polyommatus icarus | 17 April | Hampshire |
| Chalkhill Blue | Polyommatus coridon | 1 July | Hampshire |
| Adonis Blue | Polyommatus bellargus | 13 May | Wiltshire |
| Holly Blue | Celastrina argiolus | 24 March | Berkshire |
| Large Blue | Glaucopsyche arion | 6 June | Somerset |
| Duke of Burgundy | Hamearis lucina | 9 April | Hampshire |
| White Admiral | Limenitis camilla | 16 June | Oxfordshire & Surrey |
| Purple Emperor | Apatura iris | 26 June | Surrey |
| Red Admiral | Vanessa atalanta | 05 Jan | Isle of Wight |
| Painted Lady | Vanessa cardui | 02 March | Somerset |
| Small Tortoiseshell | Aglais urticae | 01 Jan | Wiltshire |
| Peacock | Inachis io | 02 Jan | Isle of Wight |
| Comma | Polygonia c-album | 04 March | Cornwall |
| Small Pearl-bordered Fritillary | Boloria selene | 12 May | Cornwall & Devon |
| Pearl-bordered Fritillary | Boloria euphrosyne | 8 April | Devon |
| High Brown Fritillary | Argynnis adippe | 3 June | Devon |
| Dark Green Fritillary | Argynnis aglaja | 6 June | Devon |
| Silver-washed Fritillary | Argynnis paphia | 13 June | Sussex |
| Marsh Fritillary | Euphydryas aurinia | 7 May | Dorset & Co. Down |
| Glanville Fritillary | Melitaea cinxia | 28 April | Isle of Wight |
| Heath Fritillary | Melitaea athalia | 20 May | Devon |
| Speckled Wood | Pararge aegeria | 19 Feb | Sussex |
| Wall Brown | Lasiommata megera | 10 April | Lancashire |
| Mountain Ringlet | Erebia epiphron | 3 June | Cumbria |
| Scotch Argus | Erebia aethiops | 22 July | Argyll |
| Marbled White | Melanargia galathea | 14 June | Oxfordshire |
| Grayling | Hipparchia semele | 17 June | Yorkshire |
| Gatekeeper | Pyronia tithonus | 24 June | Yorkshire |
| Meadow Brown | Maniola jurtina | 30 May | Sussex |
| Ringlet | Aphantopus hyperantus | 12 June | Somerset |
| Small Heath | Coenonympha pamphilus | 27 April | Sussex |
| Large Heath | Coenonympha tullia | 5 June | Co. Fermanagh & Wrexham |
These first sightings are gathered as the butterfly season progresses so as to provide up-to-date information about species emergence. They are not reviewed retrospectively by reference to transect data or distribution records and therefore represent what we believed to be the first report of a species at the time rather than a comprehensive analysis of the actual first dates recorded in a particular year.