Updates from March 3, 2011

Mayflies

Caddisflies

Stoneflies

Closeup insects by Entoman from the Lower Yuba River in California

Rhithrogena morrisoni (Western March Brown) Mayfly Nymph

View 4 PicturesSize - (excluding tails) - 12 mm
Status at time of photo - preserved, but photographed within days of capture.

W. C. Day, Aquatic Insects of California differentiates morrisoni nymphs by submedian pale dots on tergites (

One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.

Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.) 8 & 9, which look to be in evidence. This is one of the "super-hatches" on this river that can be prolific March through April.

Entoman

Collected March 3, 2011 from the Lower Yuba River in California
Added to Troutnut.com by Entoman on November 1, 2011

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Jargon Defined:

Nymphs: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).

One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.

Tergites: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.