The iCollections dataset comprises the records of all the British and Irish butterfly specimens in the entomological collections of the Natural History Museum, London. iCollections was a project to develop protocols and procedures to undertake mass digitisation of specimens, in this case British and Irish Lepidoptera. A key aspect to the digitisation effort was to make data available to support topical research. In the case of iCollections this was looking at the effects of climate change on butterfly emergence times.

The dataset comprises records of 181,545 specimens each with an image, locality, collector and date of collection (if available). The dataset extends from 1819 until the 1980s. The majority of specimens were collected from southern England, particularly the counties around London, but also the New Forest, Torbay and the Lake District. In addition to wild caught specimens, there is a large number of specimens which were specifically bred to provide good examples of particular species.