| Examples: | mayflies |
| Wings: | 4 (rarely 2) hindwings small |
| Mouthparts: | vestigial |
| Usual number of tarsal segments: | 3-5 |
| Metamorphopsis: | simple; nymphs aquatic |
| Usual size: | medium |
| Where usually found: | near water |
| Other Promimnent Features: | 3 caudal appendages; soft bodied; larvae have leaflike gills along sides of abdomen |