| Omalium Gravenhorst, 1802 |
| Omalium anceps Sharp, 1887 |
| Omalium atomarium Fauvel, 1865 |
| Omalium incultum Sharp, 1887 |
| Omalium laesicolle Mäklin, 1852 |
| Omalium laeticulum Sharp, 1887 |
| Omalium meximontanum Thayer, 2001 |
| Omalium pumilio Sharp, 1887 |
| Omalium sordidum Sharp, 1887 |
| Omalium xanthopterum Fauvel, 1865 |
| Omostilicus Casey, 1905 |
| Omostilicus sonorinus Casey, 1905 |
| Onthostygnus Sharp, 1884 |
| Onthostygnus fasciatus Sharp, 1884 |
| Onthostygnus pollens Sharp, 1885 |
| Ophioglossa Fauvel, 1866 |
| Ophioglossa (Antrogastra) Bernhauer, 1912 |
| Ophioglossa (Antrogastra) mexicana (Bernhauer, 1929) |
| Opithes Blackwelder, 1952 |
| Opithes crandalli Moore, 1974 |