Troutnut.com Fly Fishing for Trout Home
User Password
or register.
Scientific name search:

> > mean one thing, write another?

The Specimen

Onocosmoecus unicolor (Great Late-Summer Sedge) Caddisfly AdultOnocosmoecus unicolor (Great Late-Summer Sedge) Caddisfly Adult View 15 PicturesI first just assumed this was Dicosmoecus based on anglers' conventional wisdom since it's a large orange "October caddis," but Creno set me straight. I should have keyed it out. After another look under the microscope, it lacks an anepisternal wart on the mesopleuron (Mesopleuron: The side of the insect mesothorax, and the part to which the fore wings are attached in mayflies.), which rules out Dicosmoecus. The midtibiae have 2 apical (Apical: Close to the apex; tip or end.) spurs and 1 pre-apical (Apical: Close to the apex; tip or end.) spur, and from there the color pattern of the wing points to Onocosmoecus. The location then narrows the species to unicolor.
Collected September 17, 2020 from the Yakima River in Washington
Added to Troutnut.com by on September 19, 2020

The Discussion

CrenoSeptember 19th, 2020, 1:19 pm
Grants Pass, OR

Posts: 302
Onocosmoecus unicolor?
TroutnutSeptember 19th, 2020, 2:19 pm
Administrator
Bellevue, WA

Posts: 2592
Didn't mean one thing and write another -- you caught me assuming the genus based on angler-entomology instead of keying it out. Oops! After closer inspection under the microscope, of course you're right.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
CrenoSeptember 20th, 2020, 11:19 am
Grants Pass, OR

Posts: 302
Interesting that the western angling lit has Dicosmoecus as orange. Within the Dicosmoecinae only Onocosmoecus is orange, the rest are dark greys to blacks when alive and, like Onocosmoecus, often faded to browns when pinned. Amphicosmoecus could be considered orangish on some speciemens but the wings are typically more grey/brown with a reddish tint, and finely speckled. Onocosmoecus unicolor is one of those very widespread species that further study will likely reveal are comprised of several species. But not to worry, it probably won't happen soon :-) I forgot to mention - thanks for the great pics.

Quick Reply

You have to be logged in to post on the forum. It's this easy:
Username:          Email:

Password:    Confirm Password:

I am at least 13 years old and agree to the rules.

Related Discussions

TitleRepliesLast Reply
Re: one of the dicosmoecins
In Onocosmoecus Caddisfly Larva by Creno
3Apr 28, 2011
by Troutnut
Re: Grannoms
In Onocosmoecus unicolor Caddisfly Larva by Martinlf
11May 22, 2008
by GONZO
Re: Confusing Caddis
In General Discussion by Lastchance
25Oct 15, 2012
by Entoman
Onocosmoecus larvae and cases
(3 more)

In the Photography Board by Millcreek
0
Re: caddis
In the Identify This! Board by Dryfly
8Mar 19, 2007
by DMM
Re: why the color ?
In Amphipoda Scud Adult by Jordash
12Sep 5, 2012
by Entoman
Re: Peculiar Heptageniid
In Female Epeorus vitreus Mayfly Spinner by Troutnut
2Oct 5, 2006
by GONZO
Re: Limestone trout suckers for nuclear spinner
In General Discussion by Martinlf
22Jun 15, 2012
by Shanti
Re: Black fly line?
In Gear Talk by COElkFreak
12Jul 2, 2015
by CaseyP
Re: egg sack color
In the Mayfly Family Heptageniidae by LittleJ
3May 20, 2007
by LittleJ
Most Recent Posts
Yea...
In the Mayfly Species Ephoron leukon by Imaxfli
Re: Fall ISO's - Au Sable
In General Discussion by Brian314 (Partsman replied)
Tippet for Doug
In Gear Talk by Martinlf
Re: TMC 518 size 32 hooks
In Fly Tying by Dbarr15 (Martinlf replied)
Re: some fish taken on a modern streamer
In Fishing Reports by Partsman (Jmd123 replied)
Re: traditional streamers- still in use?
In General Discussion by Roguerat (Wbranch replied)
Re: fall colors
In Fishing Reports by Partsman (Wbranch replied)