Peter Schwarz/ BIA / Dryad (Minois dryas) butterfly, Poland

Wim van den Heever / Julia heleconia (Dryas julia) butterfly on head of Yacare caiman (Caiman yacare) Pantanal, Brazil.

Wild Wonders of Europe / Hermansen / Mountain avens (Dryas octopetala) seedhead, Burren National Park, County Clare, Republic of Ireland, June 2009

Wild Wonders of Europe / Zupanc / White dryas or Mountain avens (Dryas octopetala) in flower growing on rock, Triglav National Park, Slovenia, July 2009

Rolf Nussbaumer / Wildflowers Mountain aven {Dryas integrifolia} and Moss campion {Silene acaulis} growing on tundra, Varanger peninsula, Arctic Norway

Gabriel Rojo / Flambeau butterfly on flower {Dryas iulia} Ibera marshes, Argentina

Pete Oxford / Flambeau butterfly (Dryas iulia). Amazon, Ecuador, South America

David Woodfall / Mountain avens (Dryas octopetala), The Burren, County Clare, Republic of Ireland, May.

Luis Quinta / Great kingfisher (Halcyon malimbica dryas) Principe Island, UNESCO World Heritage Site, Democratic Republic of Sao Tome and Principe, Gulf of Guinea.

Nick Hawkins / Julia butterfly (Dryas iulia) photographed on white. Costa Rica.

Nick Hawkins / Julia butterfly (Dryas iulia) puddling on the head of Black wood turtle, (Rhinoclemmys funerea) in lowland rainforests, Southeastern Nicaragua. August.

Paul Harcourt Davies / Mountain avens (Dryas octopetala) wide angle view, Mt Terminillo, Lazio, Italy, July.