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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Dorsal view of a Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Nymph from the East Fork Issaquah Creek in Washington
This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Caddisfly Genus Rhyacophila (Green Sedges)

The large free-living larvae of the Rhyacophila genus are among the best-known caddisflies, and for good reason, because their unique biology is both interesting to entomologists and compatible with trout fishing. There are over 100 species, and many of them can be important.

Where & when

In 1213 records from GBIF, adults of this genus have mostly been collected during June (24%), July (21%), May (19%), August (17%), September (7%), and April (5%).

In 610 records from GBIF, this genus has been collected at elevations ranging from 10 to 23622 ft, with an average (median) of 3652 ft.

Genus Range

Hatching behavior

Habitat: Riffles

The pupae swim quickly up through the riffles and emerge on the surface.

Egg-Laying behavior

Habitat: Riffles

The females dive or crawl underwater to oviposit. When they're done they let go and dead-drift, floating slowly to the surface.

Larva & pupa biology

Diet: For most species, other aquatic insects.

Current speed: Fast

Environmental tolerance: Most species require cool water

Shelter type: No case

Rhyacophila larvae are large, usually green, and always plump, and they don't build cases or nets. They roam freely about the fast water and they often drift loose, where they are a good food for trout.

Many of these larvae have no gills at all and rely on absorbing oxygen from the water through their skin. Only cold water and fast flows can meet these needs, so Rhyacophila caddisflies love the same habitat as trout.

The larvae may rappel between the rocks on a line of brown silk they secrete. This can be imitated by coloring the last foot or so of one's leader with a brown marker.


To determine whether a specimen of Rhyacophilidae belongs to Rhyacophila, use the Key to Genera of Rhyacophilidae Adults.

Rhyacophila Fly Fishing Tips

Gary LaFontaine wrote some good tips in Caddisflies about fishing appropriate flies for the water you're covering:

A good imitaiton of a Rhyacophila larva is going to catch a lot of trout in swift, bouncing stretches of stream. The same fly is going to do poorly in slow areas of the same stream.

A fly fisherman can avoid wasting time in the wrong sections of a stream by working leap-frog fashion instead of in a straight line. If he is using an imitaiton of a fast-water insect he should fish only the swift, broken currents, skipping past the slower current areas. Likewise, if he is using an imitation of a slow-water insect he should only cover the quieter pools and flats.

He was speaking about fishing Rhyacophila imitations, but the advice is equally applicable to many aquatic insects. He cautions against using these imitations where the real insects are not abundant in the drift, because they are otherwise too large and bright to seem realistic.

Specimens of the Caddisfly Genus Rhyacophila

1 Adult
3 Pupae
9 Larvae

Start a Discussion of Rhyacophila


Caddisfly Genus Rhyacophila (Green Sedges)

119 species (Rhyacophila accola, Rhyacophila acutiloba, Rhyacophila alabama, Rhyacophila alberta, Rhyacophila alexanderi, Rhyacophila amabilis, Rhyacophila amicis, Rhyacophila appalachia, Rhyacophila arcella, Rhyacophila ardala, Rhyacophila arnaudi, Rhyacophila atrata, Rhyacophila autumnalis, Rhyacophila balosa, Rhyacophila banksi, Rhyacophila belona, Rhyacophila betteni, Rhyacophila blarina, Rhyacophila bruesi, Rhyacophila californica, Rhyacophila carolae, Rhyacophila carpenteri, Rhyacophila cerita, Rhyacophila chandleri, Rhyacophila chilsia, Rhyacophila chordata, Rhyacophila colonus, Rhyacophila complicata, Rhyacophila darbyi, Rhyacophila doddsi, Rhyacophila donaldi, Rhyacophila ebria, Rhyacophila ecosa, Rhyacophila fenderi, Rhyacophila formosa, Rhyacophila gemona, Rhyacophila glaciera, Rhyacophila haddocki, Rhyacophila harmstoni, Rhyacophila hyalinata, Rhyacophila inculta, Rhyacophila insularis, Rhyacophila invarius, Rhyacophila iranda, Rhyacophila jenniferae, Rhyacophila jewetti, Rhyacophila karila, Rhyacophila kernada, Rhyacophila kiamichi, Rhyacophila kincaidi, Rhyacophila kondratieffi, Rhyacophila latitergum, Rhyacophila ledra, Rhyacophila leechi, Rhyacophila lineata, Rhyacophila lurella, Rhyacophila malkini, Rhyacophila milnei, Rhyacophila minora, Rhyacophila montana, Rhyacophila mosana, Rhyacophila mycta, Rhyacophila neograndis, Rhyacophila nevadensis, Rhyacophila newelli, Rhyacophila nigrita, Rhyacophila norcuta, Rhyacophila novarotunda, Rhyacophila ophrys, Rhyacophila oregonensis, Rhyacophila oreia, Rhyacophila oreta, Rhyacophila otica, Rhyacophila pacifica, Rhyacophila parantra, Rhyacophila pennsylvanica, Rhyacophila perda, Rhyacophila perplana, Rhyacophila pichaca, Rhyacophila potteri, Rhyacophila rayneri, Rhyacophila reyesi, Rhyacophila rickeri, Rhyacophila robusta, Rhyacophila rotunda, Rhyacophila sequoia, Rhyacophila shenandoahensis, Rhyacophila sibirica, Rhyacophila sierra, Rhyacophila siskiyou, Rhyacophila soror, Rhyacophila spinata, Rhyacophila starki, Rhyacophila tamalpaisi, Rhyacophila teddyi, Rhyacophila tehama, Rhyacophila tralala, Rhyacophila tucula, Rhyacophila unimaculata, Rhyacophila unipunctata, Rhyacophila vaefes, Rhyacophila vagrita, Rhyacophila valuma, Rhyacophila vao, Rhyacophila vedra, Rhyacophila velora, Rhyacophila vemna, Rhyacophila vetina, Rhyacophila vibox, Rhyacophila vinura, Rhyacophila viquaea, Rhyacophila visor, Rhyacophila vobara, Rhyacophila vofixa, Rhyacophila vu, Rhyacophila vujuna, Rhyacophila vuzana, Rhyacophila wallowa, and Rhyacophila willametta) aren't included.
Genus Range
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