Butterflies of Northern Europe is a unique, comprehensive reference work that fits in your pocket.

The app contains detailed descriptions of the 168 butterfly species found in northern Europe, from northern France in the south to Greenland in the north. Written by butterfly experts Lars Andersen and John Vergo, the meticulous content covers everything from a species’ appearance to its distribution and habits, illustrated with photos of the male, female, eggs, caterpillars and host plants, together with flight period charts and distribution maps. The 31 comparison panels show different but easily confused species side by side, and their distinguishing characteristics are highlighted and described with hitherto unseen precision in over 300 photos with arrowed references and captions.

You can write notes on each species and add your sightings to a trip list to keep track of the day’s observations and even share them with others by SMS, email or social media. The app does not require an Internet connection, so it works in the field, too.

The search function makes it easy to track down a particular species by criteria such as size, colours and wing shape, making it a simple matter to find and identify that species you saw while out and about.

With its many functions and in-depth content, this app is both a field guide that goes everywhere with you and a unique, beautifully illustrated work of reference.