Bitterroot River Insect Hatches. This is a chart of the major insect hatches in the Bitterroot referenced to time of year and water temperature. Andy has guided for over 40 years on the Bitterroot and knows these hatches from both the scientific point of view and from personal experience. Each hatch includes the common name, scientific name and a favorite Carlson dry fly for each hatch.
We have three separate peaks in our trout fishing season in Western Montana.
The first is March 15 to April 30. Skwala Parallela (#10 Golden Stonefly), Leuctridae (#12 Stonefly) and Nemoridae (#14 Stonefly) all start hatching in the month of March. April has the ambiguous Blue Winged Olives (#18 abd #16 Baetis), Grey Caddis, and a minor Green Drake(#12 Ameletus connectus).
Peak number two occurs between June 20 and July 25. Many species and sizes of Pale Morning Duns, Blue Winged Olives and a Green Drake dominate the mayflies. Another species of Golden Stonefly and lesser stoneflies including the early Giant Stonefly occur during this time period.
The last peak happens between September 7 and October 20. The fall Green Drake (#10 E. hecuba) and Mahogany Dun(#12 Paraleptophlebia) dominate the hatches. Smaller mayflies hatch in tremendous quantities To complete the fall season. (#16 Rithrogena, Bactis)