This is an app for Apple devices covering 463 species of European butterflies. The 2,500 photographs are all contained within the app, so there are no roaming charges when travelling and there is no need for a phone signal.
I was lucky enough to be part of a group of lepidoptera enthusiasts who spent an annual week in a European country. One of our group was particularly dedicated to butterfly photography and I felt that his work deserved a wider audience.
Butterflies of Europe, an app for Apple devices, was the result of this, with the additional collaboration of a couple of extremely knowledgeable photographers in Switzerland.