Header image
Enter a name
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.

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 Arthroplea bipunctata

Where & when

In 11 records from GBIF, adults of this species have been collected during June (45%), July (27%), and May (27%).

Species Range

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.

Male Spinner

Body length: 6 mm
Wing length: 8 mm

Head deep dark brown; clypeus hyaline. Thorax deep dark brown. Fore femur deep brown; tibia pale brown; tarsus dirty whitish. Basal fore tarsal joint about 2/3 the length of the second. Middle and hind legs dull yellowish; median and apical dark spots on femora; tarsal joinings and claws dark brown. Wings hyaline; a faint brownish stain at extreme base, much as in Choroterpes basalis. Longitudinal veins pale brown; cross veins colorless, indistinct except in the apical costal area. Abdominal tergites deep blackish brown; sternites somewhat paler, posterior margins narrowly dull whitish, “this color on the rear segments extending to the lateral portions of the dorsum” (McD.). Tails whitish, joinings narrowly dark brown. Genitalia as in fig. 112.

Start a Discussion of Arthroplea bipunctata


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

Mayfly Species Arthroplea bipunctata

Species Range
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy