A flight intercept trap was used for 12 days on Barro Colorado Island, Panama, to assay the diversity of staphylinid beetles, and to provide data on which are diurnal and/or nocturnal. The trap was sampled twice over a 24 h period, providing data for diurnal/nocturnal activity for these beetles. In total 1,349 specimens and 35 genera of Staphylinidae were caught, representing nine subfamilies. Of these 1,349 specimens, 1036 (76.8%, P < 0.01 t-test) were caught during the day, and 313 (23.2%) were caught during the night. Aleocharinae is the most abundant subfamily (57.5%), followed by Staphylininae (13.1%). Details are given for the diurnal/nocturnal activity of each taxon captured.