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.

A small spring creek in Wisconsin. A little brook trout stream tumbles over boulders

Stream photos

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Ephemerella mucronata Mayfly Nymph Ephemerella mucronata Mayfly Nymph

Dorsal view of a Ephemerella mucronata (Ephemerellidae) Mayfly Nymph from the Yakima River in Washington

This is an interesting one. Following the keys in Merritt R.W., Cummins, K.W., and Berg, M.B. (2019) and Jacobus et al. (2014), it keys clearly to Ephemerella. Jacobus et al provide a key to species, but some of the characteristics are tricky to interpret without illustrations. If I didn't make any mistakes, this one keys to Ephemerella mucronata, which has not previously been reported any closer to here than Montana and Alberta. The main character seems to fit well: "Abdominal terga with prominent, paired, subparallel, spiculate ridges." Several illustrations or descriptions of this holarctic species from the US and Europe seem to match, including the body length, tarsal claws and denticles, labial palp, and gill shapes. These sources include including Richard Allen's original description of this species in North America under the now-defunct name E. moffatae in Allen RK (1977) and the figures in this description of the species in Italy.

17 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.

little green stonefly

This topic is about the Insect Order Plecoptera

Stoneflies are the largest of the three main types of trout stream insects. While far less important than caddis and mayflies in the East and Midwest where they are mostly thought of as handy nymphs to imitate when nothing much is hatching, it's in the West where this order comes into its own. They can cause outstanding fishing, and on many rivers their hatches are the premier events of the season.

The year begins with the little dark stoneflies of the Capniidae, Leuctridae, and Nemouridae families as some of the only active aquatic insects available to trout. As the year progresses into late Winter and early Spring, the Large Springflies of the Perlodidae family in the West and Willowflies of the Taeniopterygidae are sometimes the first dry-fly insects of the season. When Spring fully arrives, so do the most significant stoneflies for the angler - the gigantic Pteronarcyidae Salmonflies of western legend. The large Golden Stones of the Perlidae supplement these hatches and are more common across the country. Summer brings on significant hatches of the Little Yellow Stones of the Perlodidae family and the little yellow or green Chloroperlidae flies that are common sights.

Example specimens

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Male Isoperla fulva (Yellow Sally) Stonefly Adult

Artistic view of a Male Isoperla fulva (Perlodidae) (Yellow Sally) Stonefly Adult from Mystery Creek #295 in Washington

Family-level ID following Merritt, Cummins, & Berg 5th Edition: 1. Thoracic gill remnants absent 2. Arms of mesosternal Y-ridge approach posterior end of furcal pits 3. Submental gill remnants short, obscure, or absent 4. Male. Note that sternum 9 (the long, dark, last segment) appears to be the 8th if you count from the front in the ventral view, because the first segment is not easily visible ventrally. 5. Male abdominal tergum 10 not divided posteriorly; Paraprocts modified as hooks. 6. Male abdominal tergum 10 simple without notches or other prominent processes. This one was tricky, because at first glance it looks like the hooks arise from tergum 10, but in fact they're coming from the paraprocts underneath. There's a medial groove on tergum 10 that could be seen as a "notch" too, but it seems by "notch" the key is referring to a notch in the margin. 7. Abdominal sternum 8 with a conspicuous lobe and sternum 7 without such a lobe. This leads to Isoperla. Among Isoperla species known in Washington, most species are ruled out by different shapes of the vesicle (the rounded posterior bump on sternum 8). Isoperla pinta is ruled out by the lack of a region of stout spinules on tergum 9. The remaining options (without knowing how to properly dissect and image the aedeagus) are Isoperla fulva, Isoperla marmorata, Isoperla tilasqua, and Isoperla gravitans, the latter of which is too large. The other three are all at least slim possibilities, but several described characteristics seem to best match Isoperla fulva, which is also mentioned as the most common western Isoperla.

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Skwala (Large Springfly) Stonefly Nymph

Dorsal view of a Skwala (Perlodidae) (Large Springfly) Stonefly Nymph from the Yakima River in Washington

This Skwala nymph still has a couple months left to go before hatching, but it's still a good representative of its species, which was extremely abundant in my sample for a stonefly of this size. It's obvious why the Yakima is known for its Skwala hatch.

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Claassenia sabulosa (Golden Stone) Stonefly Nymph

Dorsal view of a Claassenia sabulosa (Perlidae) (Golden Stone) Stonefly Nymph from the Yakima River in Washington

Hoss
Scottsdale, Arizona

Posts: 2

Hoss on Apr 28, 2013April 28th, 2013, 9:14 pm EDT

I was just at my local river and the fish were pounding the surface. I was able to identify the fly on the water as a little green stonefly and am very interested in some good patterns to tie to imitate it. Any and all suggestions would be appreciated.

Martinlf

Moderator
Palmyra PA

Posts: 3047

Martinlf on Apr 29, 2013April 29th, 2013, 6:27 am EDT

An elk hair caddis with a lime green body and light wing should catch many of these fish. Or try a trude style caddis with a lime green body, long clear/white or ginger antron wing and ginger hackle. The internet will have lots of other patterns.

"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell

PaulRoberts

Colorado

Posts: 1776

PaulRoberts on Apr 29, 2013April 29th, 2013, 7:36 am EDT

I've seen clouds of little greens and little yellows, and rarely found them in trout stomachs. At least in appropriate proportion. Maybe just a lack of observations on my part.

Are you sure it was the stones they were on? Not Baetis, or a midge?

Hoss
Scottsdale, Arizona

Posts: 2

Hoss on Apr 29, 2013April 29th, 2013, 10:24 am EDT

Thanks on the fly ideas I will give those a shot. And as well will check the stomach's of the next couple to see if something else is coming of that I did not see. And let you know. I did see a few caddis out but very few and the little stones where fluttering all over the waters surface

Jodea

Galway city Ireland

Posts: 13

Jodea on May 2, 2013May 2nd, 2013, 1:12 pm EDT

Could get a container and collect a few .. after studying there distinctions under a microscope and then tie some up , or you can either use the live fly directly to see the varied responce from the trout or release them and watch there movement on the water to asertain how best to present them ..
I had a similar day on a very clear trout river here in Ireland ,, i had spotted a good size trout in a fast current taking something off the surface ..after dragging my net through the folage and grass on the bank i realised there was a lot more crane fly than any other,i tryed a few artificial fly first crane fly patterns and many other rising him only once and missing. then i tryed the live fly and gently cast a small live crane fly .. wham first cast and a sure take too , was a nice 2.5lb wild brown trout (released then after)