Hatch calendars, fly matches, and forage profiles — insects trout rise to, baitfish they chase, and the rivers where each bug matters most.
33 profiles
Hatches & forage
26 Insects / 7 Forage
From mayflies to streamers
52 rivers
Linked hatch calendars
Science-based
Entomology with angler notes
(Trichoptera)
Caddis are a staple Idaho trout food, with fishable larva, pupa, and adult stages in many waters.
(Acrididae)
A high-value late-season terrestrial that draws violent strikes when wind or clumsy hops dump adults into the water.
(Baetis)
A small, dependable mayfly hatch that keeps Idaho trout looking up in cool-weather windows.
(Ephemerella excrucians)
A dependable mayfly match when trout key on pale nymphs, emergers, duns, and spent spinners.
(Chironomidae)
Midges are tiny, abundant trout food that matter year-round in both rivers and stillwaters.
(Formicidae)
A simple summer prospecting bug, ants are common bank-side terrestrials that trout rarely ignore.
Formicidae
Formicidae · Egg, Larvae, Pupa, Adult
Cyprinidae
Cyprinidae · Forage · Fry
Coleoptera
Coleoptera · Eggs, First Instar, Second Instar, Third Instar, Pupa, Adult
Baetis
Baetidae · Eggs, Nymph, Emerger, Dun, Spinner, Egg Laying Spinner, Spent Spinner
Ephemera simulans
Ephemeridae · Eggs, Nymph, Emerger, Dun, Spinner, Egg Laying Spinner, Spent Spinner
Trichoptera
Trichoptera · EGGS, FREE LIVING LARVA, CASED CADDIS, PUPA, EMERGING ADULT, ADULT CADDIS, EGG LAYING ADULT
Callibaetis
Baetidae · Eggs, Nymph, Emerger, Adult / Dun, Spinner, Egg Laying Spinner, Spent Spinner
Pacifastacus leniusculus
Astacidae · Forage · Eggs, Hatchlings, Juvenile, Subadult, Adult
Zygoptera
Odonata · Egg, Nymph, Emergence, Adult
Anisoptera
Various families · Egg, Nymph, Emergence, Adult
Drunella flavilinea
Ephemerellidae · Eggs, Nymph, Emerger, Dun / Adult, Spinner, Egg Laying Spinner, Spent Spinner
Anura
Various families · Forage · Frog Spawn, Eggs, Tadpole, Tadpole w/ Back Legs, Tadpole w/ Legs, Froglet, Adult
Calineuria californica
Perlidae · Eggs, Nymph, Mature Nymph, Emerger, Adult, Egg Laying Female
Brachycentrus
Brachycentridae · Eggs, Free Living Larva, Cased Caddis, Pupa, Emerging Adult, Adult Caddis, Egg Laying Adult
Acrididae
Acrididae · Eggs, Nymph, Molting Nymph, Adult
Siphlonurus
Siphlonuridae · Eggs, Nymph, Emerger, Dun / Adult, Spinner, Egg Laying Spinner, Spent Spinner
Drunella grandis
Ephemerellidae · EGGS, Nymph, Emerger, Dun / Adult, Spinner, Egg Laying Spinner, Spent Spinner
Timpanoga hecuba
Ephemerellidae · Eggs, Nymph, Emerger, Dun / Adult, Spinner, Egg Laying Spinner, Spent Spinner
Hirudinea
Aquatic Worm · Forage · Egg Cocoons, Juvenile, Feeding Adult, Mature Adult, Mating Adults
Paraleptophlebia
Leptophlebiidae · Eggs, Nymph, Emerger, Dun, Spinner, Egg-Laying Spinner, Spent Spinner
Rhithrogena morrisoni
Heptageniidae · Eggs, Nymph, Emerger, Adult / Dun, Spinner, Egg Laying Spinner, Spent Spinner
Chironomidae
Chironomidae · Eggs, Larva, Pupa, Adult Midge, Egg Laying Adult
Peromyscus maniculatus
Cricetidae · Forage · Pups, Furred Pup, Juvenile, Mature Adult
Dicosmoecus
Limnephilidae · Egg, Free-Living Larva, Cased Larva, Pupa, Emerging Adult, Adult, Egg-Laying Adult
Ephemerella excrucians
Ephemerellidae · Eggs, Nymph, Emerger, Dun, Spinner, Egg Laying Spinner, Spent Spinner
Epeorus albertae
Heptageniidae · Eggs, Nymph, Emerger, Dun / Adult, Spinner, Egg Laying Spinner, Spent Spinner
Pteronarcys californica
Pteronarcyidae · Eggs, Nymph, Mature Nymph, Emerger, Adult Salmonfly, Mating Adults, Egg Laying Female
Amphipoda
Crustacean · Forage · Juvenile, Adult
Cottus
Cottidae · Forage · Egg Mass, Fry, Juvenile, Adult, Spawning Adults
Skwala
Perlodidae · Egg, Nymph, Mature Nymph, Emerger, Adult, Egg Laying Female
Tricorythodes
Leptohyphidae · Eggs, Nymph, Emerger, Dun, Spinner, Egg Laying Spinner, Spent Spinner
Corixidae
Nymph, Adult
Isoperla
Perlodidae · Eggs, Nymph, Mature Nymph, Emerger, Adult Stonefly, Egg Laying Female
This guide connects entomology references, hatch charts, and field-guide knowledge to practical profiles. Identification and life-cycle science are separated from fly-matching advice so you can trust what you read on the water.
Each profile links to featured waters where the bug appears, matching fly patterns, and fish species that prey on it. Coverage expands as we publish more rivers and research.
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