| Orthocentrus albofasciatus Provancher, 1883 |
| Orthocryptus Viereck, 1913 |
| Otlophorus Förster, 1868 |
| Otlophorus affinis LeGuillou, 1841 |
| Otoblastus Förster, 1869 |
| Otoblastus fuscipennis (Cameron, 1904) |
| Otoblastus phaeopteris (Townes & Townes, 1950) |
| Otohimea Uchida, 1926 |
| Oxypimpla Noskiewicz & Chudoba, 1951 |
| Oxytaenia Förster, 1869 |
| Oxytaenia barda (Cresson, 1868) |
| Oxytaenia barda subsp. carolina (Townes, 1962) |
| Oxytaenia melanopoda (Cameron, 1885) |
| Oxytaenia rufolineata Cameron, 1904 |
| Oxytaenia semifumata (Cameron, 1885) |
| Pachysoma Szépligeti, 1916 |
| Pachysoma albopictus (Szépligeti, 1916) |
| Pachysomoides Strand, 1917 |
| Pachysomoides fulvus (Cresson, 1864) |
| Pachysomoides stupidus (Cresson, 1874) |