Oryssus abietinus, [506];

O. sayi, [506]

Osborn on Menopon, [350]

Osmylides, [466]

Osmylina, [466]

Osmylus chrysops, [341];

larva, [466];

O. maculatus, [466]

Osten Sacken on similar gall-flies, [532]

Ostia, [48] f., [133], [435]