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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 Grammotaulius betteni (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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 Family Psychomyiidae

Two species of this small family may be very abundant and important to the angler, Psychomyia flavida and Lype diversa.

Where & when

In 254 records from GBIF, adults of this family have mostly been collected during June (28%), July (22%), May (19%), and August (14%).

In 154 records from GBIF, this family has been collected at elevations ranging from 20 to 8924 ft, with an average (median) of 2342 ft.

Family Range

Hatching behavior

The pupae emerge by swimming to the surface.

Egg-Laying behavior

Females dive to the bottom of the river to lay their eggs.

Larva & pupa biology

Diet: Algae, leaves, animal matter

Shelter type: Silk tube attached to underwater surfaces and covered with various types of stream debris

Start a Discussion of Psychomyiidae


Caddisfly Family Psychomyiidae

Genus in Psychomyiidae: Lype, Psychomyia
2 genera (Paduniella and Tinodes) aren't included.
Family Range
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