New: the free Wasatch Flies Field Guide, with bug ID, a hatch calendar, fly picks, rigs and knots. Read it online or download the PDF.

Mountain streams wake up first, with midges and Blue-Winged Olives in late winter and caddis, stoneflies and mayflies through spring and early summer. Alpine lakes open after runoff, and their damsels, Callibaetis and chironomids run a few weeks behind valley water.

How to read the chart: each row is a bug, with typical hook sizes. Dark cells marked Peak are the best months; light cells marked ✓ mean the bug is around. Green month headers show David’s guiding season (April–June and September–October). The last column links a Wasatch Flies pattern that fishes well for it. On a phone, each bug shows as its own card.

Month-by-Month Hatch Chart

What’s on the water month by month in our mountain streams and alpine lakes. Elevation, snowpack and runoff shift timing by weeks, so use this as a guide, not a calendar.

Peak✓ PresentGuide season: Apr–Jun & Sep–OctJul–Aug: no trips (heat)

Bug	Hook	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Wasatch Flies pick
Midges	#18–24	Peak	Peak	Peak	✓	✓	✓	✓	✓	✓	✓	Peak	Peak	Real McCoy Micro, Tungsten Blue Grey & Copper
Blue-Winged Olives (Baetis)	#18–22			Peak	Peak	✓	✓			✓	Peak	Peak	✓	Tungsten Blue Grey & Copper, Olive Warrior
March Browns	#12–14				Peak	Peak								The Real McCoy
Mother’s Day Caddis	#14–16				✓	Peak								Tungsten Caddis Green & Copper
Caddis (summer/fall)	#14–18					✓	Peak	Peak	Peak	✓	✓			Tungsten Caddis Green & Copper
Salmonflies & Golden Stones	#4–10					✓	Peak	✓						The Real McCoy
Yellow Sallies	#14–16						Peak	Peak	✓					Brown Sugar Perdigon
PMDs (Pale Morning Duns)Timing depends on elevation and water temperature: lower, warmer water hatches first.	#14–18					✓	Peak	Peak	✓					Brown Sugar Perdigon, The Real McCoy
Green Drakes	#10–12						✓	Peak	✓					The Real McCoy
Tricos	#20–24							✓	Peak	Peak				Shop flies
Terrestrials (hoppers, ants, beetles)	#8–18						✓	Peak	Peak	Peak	✓			Shop flies
October Caddis	#8–10									✓	Peak			Shop flies
Mahogany Duns	#14–16									✓	✓			Brown Sugar Perdigon
Scuds & Sow Bugs	#12–18	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	The Real McCoy
Leeches & Streamers	#4–10	✓	✓	✓	Peak	✓	✓	✓	✓	✓	Peak	Peak	✓	Shop flies
Damsels (lakes)	#10–14						✓	Peak	✓					Shop flies
Callibaetis (lakes)	#14–18					✓	Peak	✓						Shop flies
Chironomids (lakes)	#12–18				✓	Peak	Peak	✓	✓	Peak	✓			Real McCoy Micro

Alpine lakes and high streams usually open up after runoff (late June–July) and run about 2–4 weeks behind valley water. Want the fish to eat it? Shop Wasatch Flies on Etsy.

Want to fish the hatch? See Guided Trips or pick up flies at the Wasatch Flies shop. For current conditions, check the latest fishing report.