What hatches in May: flies and patterns

11 entries in the Hatch Window curated chart are typically active in May, with the fly patterns that match each.

By water type

• Tailwater: Midges, Caddisflies (general), Sulphur, Scuds & Sowbugs, Yellow Sally (Little Yellow Stonefly)
• Freestone: Midges, Caddisflies (general), Salmonfly / Golden Stonefly, Hendrickson, Sulphur, March Brown, Grannom Caddis, Green Drake (Eastern) / Coffin Fly, Yellow Sally (Little Yellow Stonefly), Light Cahill
• Spring creek: Midges, Caddisflies (general), Hendrickson, Sulphur, Grannom Caddis, Scuds & Sowbugs, Light Cahill

Hatches and matching patterns

Midges

• Zebra Midge (nymph, size 18-22)
• Griffith's Gnat (dry, size 18-22)
• Rojo Midge (nymph, size 20-24)

Year-round on tailwaters, most reliable hatch on cold winter days when little else is moving.

Caddisflies (general)

• Elk Hair Caddis (dry, size 14-18)
• Sparkle Pupa (emerger, size 14-18)
• LaFontaine's Deep Sparkle Pupa (nymph, size 14-16)

The spring "Mother's Day caddis" emergence is a marquee Western event on rivers like the Arkansas.

Salmonfly / Golden Stonefly

• Chubby Chernobyl (dry, size 4-8)
• Stimulator (dry, size 6-10)
• Pat's Rubber Legs (nymph, size 4-8)

Large, loud, and short-lived; hatch progresses upstream with warming water, so timing follows elevation.

Hendrickson

• Hendrickson Dry (Catskill-tie) (dry, size 12-14)
• Red Quill (dry, size 12-14)
• Hare's Ear Nymph (nymph, size 12-16)

The classic early-season Catskill hatch, the pattern that launched American dry-fly tying on rivers like the Beaverkill and Willowemoc.

Sulphur

• Sulphur Comparadun (dry, size 16-18)
• Sulphur Dun (dry, size 16-18)
• Sulphur Pheasant Tail (nymph, size 16-18)

A reliable evening hatch on Eastern freestones and Midwest spring creeks alike; a smaller fall emergence follows the main late-spring one.

March Brown

• March Brown Dry (dry, size 10-14)
• March Brown Nymph (nymph, size 10-14)

Big, mottled mayfly on Eastern freestones; a good bet on overcast late-spring afternoons.

Grannom Caddis

• Black Caddis (Elk Hair) (dry, size 16-18)
• Green Weenie (nymph, size 12-14)
• Deep Sparkle Pupa (dark) (emerger, size 16-18)

An early-spring blizzard hatch on Eastern and Midwest freestones/spring creeks, often nicknamed the "apple caddis" for coinciding with apple blossoms.

Green Drake (Eastern) / Coffin Fly

• Green Drake Extended Body (dry, size 8-10)
• Coffin Fly (spinner) (dry, size 8-10)
• Green Drake Nymph (nymph, size 8-10)

A different, larger species from the Western Green Drake, Penn's Creek's famous short, intense late-spring emergence.

Scuds & Sowbugs

• Scud (olive/tan) (nymph, size 14-18)
• Sowbug (nymph, size 14-18)

Not a hatch, a year-round staple on cold, stable tailwaters and spring creeks (the South Holston and Clinch in Tennessee, the Bighorn and San Juan out West, Pennsylvania limestoners, the Driftless Area) where crustaceans outnumber insects.

Yellow Sally (Little Yellow Stonefly)

• Yellow Sally Dry (dry, size 14-16)
• Yellow Stimulator (dry, size 14-16)
• Little Yellow Stone Nymph (nymph, size 14-16)

A small, bright-yellow summer stonefly found across Western, Northeastern and Southern Appalachian streams; fluttering egg-layers draw fish on warm afternoons and evenings.

Light Cahill

• Light Cahill Dry (dry, size 12-16)
• Light Cahill Comparadun (dry, size 14-16)
• Light Cahill Nymph (nymph, size 12-16)

A creamy, pale-yellow evening mayfly of late spring and early summer across Eastern, Midwest and Southern Appalachian freestones; a classic dusk dry-fly hatch.

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