Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York

Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

Stream photos

Featured on the forum

Re: Trico emergers
In the Mayfly Genus Tricorythodes by Bwoklink (Martinlf replied)

Re: Trico Tips
In the Mayfly Genus Tricorythodes by Martinlf

Re: UV spectrum and trout
In General Discussion by Martinlf

Re: closing the gender gap in flyfishing
In General Discussion by Konchu (Smallflyguy replied)

Re: Fishing Kupa River, Slovenia
In Fishing Reports by Slocum (Fish1 replied)

Hydropsyche (Spotted Sedge) Caddisfly Larva Hydropsyche (Spotted Sedge) Caddisfly Larva

Ventral view of a Hydropsyche (Hydropsychidae) (Spotted Sedge) Caddisfly Larva from the Yakima River in Washington

With a bit of help from the microscope, this specimen keys clearly and unsurprisingly to Hydropsyche.

9 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 Callibaetis montanus (Speckled Duns)

Where & when

In 1 records from GBIF, adults of this species have been collected during July (100%).

Species Range

source

Map of specific collection sites

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: 6 mm
Wing length: 8 mm

A brownish yellow species; cross veins of fore wing few in number; marginal intercalaries occur singly; male not known.

“Body discolored; notum testaceous, irrorated on each side with brown ochre, and traversed lengthwise by a median brown-ochreous stripe intersected by a light yellowish line” (Eaton). Legs “somewhat of a dull light Vandyke brownish-grey, stippled or irrorated minutely and densely in the femora with very light burnt umber brown”; tarsal joinings similar in color; distal joints of the tarsi darkened, claws black. Wings vitreous; cross veins of fore wing few in number, intercalaries single. Costal vitta light raw-umber brown in color, occupying the costal, subcostal and “next adjoining spaces,” and widened at the base of the wing; this band varies in intensity apically and in the basal costal space. Veins similar in color, except the basal costal cross veins, which are whitish. 6 or 7 cross veins before the bulla; beyond it “about 7 rudimentary and 7 well-defined simple and almost straight” cross veins. Tails white; joinings and basal joints yellowish.

Start a Discussion of Callibaetis montanus

References

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