Aeolus Eschscholtz, 1829 .

Most Montana records of Aeolus mellillus (Say) are incorrect and should be treated as Aeolus livens (LeConte) (Fig. 1a), which can be common in agricultural fields. There is also a discrepancy between the aedeagus descriptions of these two species in Lin (1997) and Johnson and Lin (1998). Based on the key and drawings in Lin (1997), our personal dissections, and the type of A. livens in the MCZC, the aedeagal descriptions provided in Johnson and Lin (1998) should be reversed. Aeolus livens has both the median lobe and the parameres acute apically, while A. mellillus has the median lobe constricted apically and the apex of each paramere broadly rounded or obtuse.