Ptiliids represent the smallest known beetles, averaging .50mm to 1.5mm in length. The female spermatheca is a valuable diagnostic character for identifying species, due to its highly variable form. Spermatozoa also exhibit varying charateristics. Female ptiliids develop eggs one at a time within the abdominal region, since egg size is generally half the body length. Adults and larvae of featherwing beetles are usually found together in a variety of habitats including moist leaf litter, mammal nests and dung, rotting cacti, ant and termite colonies, under bark of dead trees, along sand and gravel banks of rivers and streams, beneath seaweed on beaches, and other habitats containing rotting or damp organic material.
Some taxa are also specialists of fungi, feeding on the spores produced by the fruiting bodies.
The two most noticeable characteristics of ptiliids are their feathery wings and minute size. The membranous area of their wings is greatly reduced, in most species consisting of only a thin strut. Attached to the edge of the wing are long setae, making up most of the functional surface of the wing. Tarsi appear 2 or 3-segmented. Cephaloplectines, while not polymorphic, lack eyes entirely, due to a myrmecophile lifestyle.