A small bug (1.5 – 2.0 mm) which generally occurs in damp leaves and moss but also found in ants’ nests. Adults appear in the late summer / autumn and overwinter. Mating occurs in spring and larvae have been found in July and August. Because of its small size and cryptic habits C. coleoptratus is probably more widespread than records suggest. Very few records have been received by the recording scheme, but NBN Gateway shows it to be distributed in England, north to Cumbria, and Wales, although it appears to be absent from west Wales (except for a record from the Llyn Peninsular) and south-west England. There are 23 records up till 1989 and 16 records from 1990 onwards.
C. coleoptratus is a dark brown bug with forewings covering the abdomen (although usually referred to as brachypterous, or short winged, because there is a longer winged form that is occasionally found). The four segmented antennae consist of two short basal segments and much longer 3rd and 4th segments, a feature also characteristic of the Dipsocoridae. The rostrum of C. coleoptratus is longer than that of the similar looking Dipsocoridae (see Species) and reaches the 2nd or 3rd visible abdominal segment.