The hot summer of 2013 may have faded from memory in the face of one of the wettest winters on record, but the long warm, sunny periods helped revive the fortunes of butterflies hit by appalling weather in summer 2012.
The small copper, small skipper and large skipper were also among the species that bounced back, according to the "wider countryside butterfly survey" run by Butterfly Conservation, the British Trust for Ornithology and the Centre for Ecology and Hydrology.
Overall, the majority of farmland butterfly species recovered in 2013 after suffering one of the worst years on record for butterflies in 2012, the study found.
The research counts butterflies in more than 850 randomly selected one kilometre squares across Scotland, England, Wales and Northern Ireland.
Recorders saw an average of 85 butterflies of five species per survey in July and August 2013, as the warm, sunny conditions allowed butterflies to fly, feed and breed, almost double what was recorded in the very wet conditions in 2012.
The small tortoiseshell, which has declined in recent years, recorded its best year since 2009.