Notice the similarities between aquatic and terrestrial insect activity during September on the South Fork and the lower Henry’s Fork. The same applies to streamer pattern effectiveness. Look for these similarities to continue through October. These fall off some for the upper Henry’s Fork where aquatic insect hatches are more diverse and brown trout are absent. BWO activity and responding trout in any of these locations is reliable this time of the season.
With unsettled weather coming up, streamer fishing for migrating browns is becoming very attractive whether from Warm River to Ashton or Ashton Dam on downstream past St. Anthony. Early or late in the day will be best regardless of weather.
Goings on along the lower river are very similar to happenings on the South Fork. No significant mutant stones but plenty of BWOs, some mahogany duns and a recommendation to try streamer flies especially under the current weather conditions.
If you intend to fish the lower river, now is the time to have streamers in that fly box. Add low light conditions like predicted for day times the rest of this week to early AM and sunset as the best times to present these.
The lower river offers some daytime fishing thanks to grass hopper populations. Next week look for fish showing more interest in tiny BWOs because of predicted stormy weather. We are in the season to begin thinking streamer presentation for brown trout especially during conditions like predicted for next week.
No drop in flow here but mayfly activity on the lower river is similar (good) to that of the South Fork. Tiny BWOs (pseudocloeon edmunsi) are coming out on the lower river in numbers good enough to interest trout into near surface feeding. That means presenting very small (#18-22) life cycle patterns. Good luck if you tie into a trophy individual using one of these patterns!
Flying ants have arrived along the upper river, so add these to the grasshopper abundance, and terrestrial insect patterns of these should accompany your visit to this part of the river. Mayflies activity is reduced to a spotty trico emergence with some speckled duns thrown in. Caddis are still active here, but seem to be less in favor than especially ants according to resident trout (and whitefish). As always occurs this time of year, extensive weed beds put some limits on wet fly fishing and make escape havens for large hooked trout (and whitefish).
Cooler mornings and less daylight means we are heading in the direction of the lower river to begin “perking up” with respect to offering better fishing. Look for the small BWO activity to become important in a few weeks and streamer fishing success to begin ramping up.
No big change here since our last report. Terrestrial insects “rule the roost” with respect to attracting trout just about everywhere on the river. Flying ants and trico spinners are coming closer to be available in important numbers up and down the river. It will take a lot of cooling off and some weeks before the late season BWO hatch begins.
Significant flying ant and trico activities are just around the corner along the upper river. For now concentrate on presenting terrestrial patterns during daytime, then switch to caddis life cycle in the evening. Try hopper- bead head dropper combos in Box Canyon, but be aware of recreational floaters there during mid-day. The same patterns apply to the warmed up lower river: those for terrestrial insects with and without droppers during daytime, those for caddis ( and streamers) during evening hours.