| Taxon |
Description |
| Ochrotrichia |
A
genus within the Purse case maker family of Caddisflies |
| Ochthebius |
A
genus within the Minute Moss Beetle family of (aquatic) Beetles |
| Octogomphus |
A
genus within the Clubtail family of Dragonflies |
| Odonata |
The
order or Damselflies & Dragonflies within Old-winged Insects |
| Odontoceridae |
The
Strong case maker family of Caddisflies |
| Odontomesa |
A
genus within the Midges family of (aquatic) True Flies |
| Odontomyia |
A
genus within the Aquatic Soldier Flies family of (aquatic) True Flies |
| Oecetis |
A
genus within the Longhorned case maker family of Caddisflies |
| Oemopteryx |
A
genus within the Winter family of Stoneflies |
| Oligoneuriidae |
The
Bushlegged family of Mayflies |
| Oligophlebodes |
A
genus within the Uenoidid case maker family of Caddisflies |
| Oligoplectrum |
A
genus within the Humpless case maker family of Caddisflies |
| Oliveridea |
A
genus within the Midges family of (aquatic) True Flies |
| Onocosmoecus |
A
genus within the Northern case maker family of Caddisflies |
| Ophiogomphus |
A
genus within the Clubtail family of Dragonflies |
| Oplonaeschna |
A
genus within the Darner family of Dragonflies |
| Optioservus |
A
genus within the Riffle Beetle family of (aquatic) Beetles |
| Ordobrevia |
A
genus within the Riffle Beetle family of (aquatic) Beetles |
| Oreodytes |
A
genus within the Predaceous Diving Beetle family of (aquatic) Beetles |
| Oreogeton |
A
genus within the Aquatic Dance Flies family of (aquatic) True Flies |
| Ormosia |
A
genus within the Crane Flies family of (aquatic) True Flies |
| Orthemis |
A
genus within the Skimmer family of Dragonflies |
| Orthocladius |
A
genus within the Midges family of (aquatic) True Flies |
| Osobenus |
A
genus within the Perlodid family of Stoneflies |
| Ostrocerca |
A
genus within the Spring Stoneflies family of Stoneflies |
| Oxyethira |
A
genus within the Purse case maker family of Caddisflies |