Fly fishing pressure on St Joe River can be high during peak season. Matching the hatch is one of the best strategies for improving your catch rate on the St Joe River in northern Idaho. The following chart lists the major hatch species, recommended fly sizes and emergence dates for Upper and Lower St Joe River.
Hatch availability and emergence dates shown in the chart below may vary year to year due to changes in weather conditions, temperature and water flows.
| Fly Hatch | Size | Date |
|---|---|---|
| PMD | 16 - 18 | June 1 - Aug 31 |
| Baetis (BWO) | 18 - 22 | Mar 15 - Apr 30; Sept 1 - Oct 15 |
| Skwala Stonefly | 8 - 10 | Mar 1 - Apr 15 |
| March Browns | 14 - 16 | May 1 - June 15 |
| Green Drake | 10 - 12 | June 1 - July 31 |
| Caddis | 16 - 18 | May 1 - June 30 |
| October Caddis | 6 - 10 | Sept 1 - Oct 31 |
| Mahogany Duns | 16 - 18 | Sept 1 - Oct 32 |
| Salmonfly | 4 - 6 | May 15 - July 15 |
| Golden Stonefly | 6 - 10 | June 1 - July 15 |
| Green Sedge | 12 - 16 | July 1 - Aug 31 |
| Yellow Sally | 12 - 16 | July 1 - Aug 31 |
| Ants | 14 - 16 | July 1 - Aug 31 |
| Beetles | 10 - 12 | July 1 - Aug 31 |
| Midges | 18 - 22 | Jan 1 - Dec 31 |
Fishing nymph patterns that match the hatch just prior to a hatch can be an effective technique for targeting trout subsurface on St Joe River.
