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.

Stream photos

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Pycnopsyche guttifera (Great Autumn Brown Sedge) Caddisfly Larva Pycnopsyche guttifera (Great Autumn Brown Sedge) Caddisfly Larva

Dorsal view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington

This specimen appears to be of the same species as this one collected in the same spot two months earlier. The identification of both is tentative. This one suffered some physical damage before being photographed, too, so the colors aren't totally natural. I was mostly photographing it to test out some new camera setting idea, which worked really well for a couple of closeups.

10 Recently Added Photos

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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Mayfly Species Campsurus decoloratus (White Flies)

Where & when

In 2 records from GBIF, adults of this species have been collected during June (100%).

Species Range

source

Map of specific collection sites

Identification

Species ID from GBIFthe Global Biodiversity Information Facility

Source: Revision of Campsurus violaceus species group (Ephemeroptera: Polymitarcyidae) with new synonymies and nomina dubia in Campsurus Eaton, 1868

Diagnosis. Campsurus decoloratus can be separated from the other species of the genus by the following combination of characters: 1) pedestals and penes similar to Campsurus violaceus, with pedestals elongate with outer corner slightly projected and penes slender, except that " thumb " is finger-like (figures 22 - 23 of Traver 1947); 2) female socket with straight transverse opening and with an anterior longitudinal rib (Figs. 45 - 46).

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Female Spinner

Described in Needham et al (1935)

Body length: 16 mm
Wing length: 14.5 mm

Mesothorax yellowish fuscous; fore legs blackish; abdomen yellowish, with lateral obscure fuscous stripes.

Head brownish-black, antennae pale. Mesothorax yellowish fuscous. Fore legs blackish, middle and hind legs yellowish. Wings hyaline, yellowish; subcosta fuscous, other veins yellowish. Abdomen yellowish, with lateral obscure fuscous stripes. Tails yellowish. (Description taken from Hagen and Eaton). (Description is probably of a female specimen.)

Description from GBIFthe Global Biodiversity Information Facility

Female. Abdominal sternum VIII with a subquadrate single socket on the anteromedian area, the anterior furrow presents a thin medial rib (" r " in Fig. 46); in both female adults studied the groove (socket`s opening) appears obtruded by a subespherical aglutinated material ("? " in Fig. 46). The sternum VIII is completely covered by microtrichiae, except anteriorly and around the groove (Figs. 45 - 46).

Eggs (Fig. 44). Length, 188 - 237; width, 145 - 175. L / W ratio (N = 5): 1.2 - 1.6. Hemispherical to ovate, with convex and concave sides as usual, capped pole broader, cap formed by> 15 very long threads coiled around each other in a single stronger filament, chorionic surface covered by small punctures, except below the polar cap. Micropylar devices unknown.

Start a Discussion of Campsurus decoloratus

References

Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.