The wings of this species are short at 4.0 to 4.5mm and no more than three times as long as broad, being equal to about 1.5 times the length of the head and thorax. (This compares with six times as long and twice as long respectively in the related C. hirundinus.) The wing tips are attenuated with the costa reaching to three quarters the length of the margin.

These flies are blood-feeding ectoparasites of Apus apus (Swift) and sometimes other Hirundines. They will usually be found on the birds themselves or in their nests.

May to August, when the host birds are present in the UK.

Common in England and Wales, becoming rarer in Scotland. Not often recorded.

Believed to be common in Leicestershire and Rutland but severely under-recorded. The Empingham record is the first for VC55.