These are the major hatches of aquatic insect as they occur during the season. These insects and others, hatch on other streams and lakes in the area, but not as predictably or as abundantly as on the waters listed.
STONEFLY
“Salmon Fly”
(Pteronarcus califonicus)
Henry’s Fork | May22 - June 15
Big Hole | June 14 - June 25
Madison | June 25 - July 10
Yellowstone | July 10 - July 25
Gallatin | July 10 - July 25
CADDIS
Many species
(Trichoptera)
Henry’s Fork | June 5 - July 15
Madison | July 1 - August 15
Firehole | June 5 - July 15
Yellowstone (Y.N.P.) | July 15 - August 15
Gallatin | July 10 - August 15
MAYFLIES
Pale Morning Dun
(Ephemerella inermis & Ephemerella infrequens)
Firehole | June 10 - June 30
Madison (Y.N.P.) | June 15 - July 5
Henry’s Fork | June 10 - June 30 & July 15 - August 31
Western Green Drake
(Ephemerella grandis)
Henry’s Fork | June 21 - July 1
Madison (Y.N.P.) | June 15 - July 10
Brown Drake
(Ephemera stimulans)
Henry’s Fork | June 25 -July 5
Gibbon | July 1 - July 10
Small Western Green Drake
(Ephemerella flavilinea)
Henry’s Fork | July 5 - July 25
Madison (C&R) | July 20 - August 10
Tiny Western Olive
(Pseudocloen edmundsi)
Henry’s Fork | July 15 - September 30
Firehole | September 15 -October 31
“Tricos”
(Tricorythodes minutes)
Hebgen Lake | July 15 - September 15
Madison (Y.N.P.) | August 1 - September 30
Henry’s Fork | August 1 - September 30
Speckled Spinner
(Callibaetis nigritus)
Hebgen Lake | July 15 - September 15
Centennial Valley Lakes | July 15 - September 10
Little Western Iron Blue Quill
(Baetis parvus & Baetis tricaudatus)
Firehole | June 10 - June 30
Madison (C&R) | May 1 - June 1 & September 20 - October 31
Yellowstone (Y.N.P) | September 20 - October 31
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