Ptiliidae contains 75 of the smallest insects in Britain, all 1mm or less in length, and includes the smallest British beetle, the ironically-named Nephanes titan (Newman). The common names comes from the distinctive structure of the wings, which often protrude from beneath the elytra when at rest.  Most species are brown or black, and many species are found in decaying organic matter, particularly compost heaps, dung heaps, grass cuttings and rotting wood, where conditions are favourable for the fungal growth that both adults and larvae graze on.

There are three subfamilies on the 2012 British list: Nossidiinae, Ptiliinae and Acrotrichinae.  Nossidiinae has just one British representative, Nossidium pillosellum (Marsham), which is found mainly in rotting elm stumps (Ulmus spp.).

Subfamily Ptiliinae includes 44 species.  Several are known in Britain from very few specimens, including Ptiliolum sahlbergi Flach, Ptiliolum caledonicum (Sharp), Oligella intermedia Besuchet, and Ptilium caesicum Erichson, while Euryptilium gillmeisteri Flach is a relatively new arrival.  Some species, notably Ptilium myrmecophilum (Allibert) and Ptenidium formicetorum Kraatz are associated with ant nests, but most occur in decaying organic matter of various kinds.

Acrotrichinae contains the remaining 30 species, also found mainly in leaf litter, dung, compost and fungi.  Nephanes titan is a member of this subfamily, and is common in old dung heaps.