British Trust for Ornithology licensed bird ringers, and other citizen scientists with an interest in entomology, collected 4365 louse flies (also known as flat flies) and keds (Diptera: Hippoboscidae) for the Mapping the UK's Flat Flies Project. The project expanded to include the Republic of Ireland and the Isle of Man as well as the United Kingdom, and includes a few flies from as early as 2002, as well as those from the main study period of 2020 - 2024. The flies included in this database are the UK Hippoboscids: louse flies: Crataerina pallida, Ornithomya avicularia, Ornithomya chloropus, Ornithomya biloba, Stenepteryx hirundinis, Pseudolynchia canariensis, Pseudolynchia garzettae, and Icosta minor, and the keds* Lipoptena cervi, Hippobosca equina* and Melophagus ovinus. This dataset included the Hippoboscid species names, year of collection, location details to an accuracy of a 10km Ordnance Survey grid square, and host species names. Only the year of collection is provided, rather than a full date; locations have been blurred to 10km, and site names are not included to protect the locations of additionally protected and other rare species of birds.

This dataset contains some of the raw data from the "Mapping the UK's Flat Flies Project" related to the host-parasite species associations. It includes data on louse flies and keds collected in the United Kingdom, the Republic of Ireland, and the Isle of Man, but British Trust for Ornithology (BTO) licensed bird ringers and other citizen scientists with an interest in entomology. Most records date from the main study period of June 2020 to January 2025, but there are a few earlier records dating back to 2002.

Volunteer bird ringers were sent collecting kits and asked to return them with any flies collected and the relevant metadata at the end of each season. Flies collected at any time - mostly as pinned specimens - were also accepted from entomologists, and anyone who wanted a Hippoboscid identified via the Hippoboscidae and Nycteribiidae Recording Scheme. Flies were identified by the author using published keys and a binocular microscope.