Waterlands
River Intelligence · Entomology

Read the Water. Match the Hatch.

Every river has an entomological fingerprint — the bugs it grows, when they hatch, and how trout eat them. Learn the bugs, cross-reference live flows, and fill your box before you go.

Hatching NowPale Morning DunGreen DrakeTricoSulphurSmall Western Red QuillFlavGray DrakeCallibaetisSpotted SedgeGolden StoneYellow SallyBrown DrakePink LadyTerrestrialsScuds & Sowbugs
EncyclopediaHatch CalendarRiver FingerprintsMatch the HatchBug School
Bug School
Everything a Trout Eats, In One Lesson
You don't need latin to catch fish — you need to know which of four insect orders is on the water, and which stage of its life the fish are eating. That's the whole game.
Mayflies
Ephemeroptera
Delicate, upright-winged sailboats of the river. Incomplete metamorphosis: nymph → emerger → dun → spinner. The classic dry-fly insect.
Nymph
Emerger
Dun
Spinner
Caddisflies
Trichoptera
Moth-like, tent-winged, and everywhere. Complete metamorphosis adds a pupa stage — the most under-fished moment in fly fishing.
Larva
Pupa
Adult
Stoneflies
Plecoptera
Big, clumsy crawlers of fast, clean water. No emergence in the film — they crawl ashore, so bank water is where the action is.
Nymph
Adult
Midges
Diptera
Tiny, year-round, and the whole menu in winter. If nothing is hatching, something is still midging.
Larva
Pupa
Adult
The Four Moments a Trout Eats a Mayfly
One bug, four different flies. Where in the water column you fish matters more than which pattern you tie on.
Bottom
1. Nymph
90% of a trout's diet, eaten near the bottom every day of the year.
Dead-drift a beadhead deep
Film
2. Emerger
The vulnerable swim to the surface. Fish eat more emergers than duns during a hatch.
Fish it in the surface film
Surface
3. Dun
The upright-wing adult drying its wings — the moment everyone pictures.
The classic dry fly
Surface
4. Spinner
Mating is done; spent bugs fall flat on the water. Easy calories at dusk.
Flat-wing spinner at dark
Reading Rise Forms
The shape of a rise tells you what stage the fish is eating.
Sip
Spinners or midges — a slow, tiny ring in flat water means easy, dead food. Fish flush-floating patterns.
Head & tail
Emergers in the film — you see the back, not the mouth. Switch from your dry to an emerger.
Splash
Caddis or fleeing bugs — violent takes mean moving food. Skate or twitch your fly.
What Triggers a Hatch
Why Waterlands cross-references bugs with live gauge data.
Water Temp
Every bug has a thermal window. Baetis pop at 44°F; PMDs want 54°F+. A gauge reading tells you what CAN hatch today.
Flow
Dropping, clearing water after a spike is prime. Rising, muddy water shuts surface activity down — check the 7-day trend, not just today.
Light
Overcast extends mayfly hatches; bright sun pushes activity to morning and dusk. The worst weather is often the best fishing.
Season
The calendar sets the cast of characters, conditions set the schedule. That's why the Match tool crosses both.
Glossary
CFS · cubic feet / second
Tailwater · below a dam
Freestone · undammed river
The Film · surface tension
Spinner Fall · mating aftermath
Dry-Dropper · two-fly rig
Runoff · snowmelt flood
Selective · picky fish
≋ Waterlands · Hatch data blends USGS gauges, NOAA temps & regional emergence records
USGS Real-time Data · Free to Start · No Credit Card