Assistance on ID of stream mayfly dun and stonefly adult

cabezon

Sculpin Enterprises
WFF Supporter
While fishing the “Agate Sand River” in Idaho two weeks ago, I encountered two insects in the evening. I have no idea of the specific identify of the first beyond a mayfly dun. The red specks on the rock appear to be mites; there is one on the wing of the dun.

NewlyEmergedMayflyNoLoc30031.jpg

I believe that the second is a male short-winged stonefly. This male appears to have just emerged; there appears to be a problem with the outer segments on the third right leg of this individuals.


ShortwingedStoneflyNewlyEmerged30185.jpg

Assistance / confirmation from the entomologists in the group would be helpful.

Thank you,

Steve
 

Taxon

WFF Moderator
Hi Steve-

I suspect the mayfly female subimago to be of genus Paraleptophlebia, but might be wrong. ;)
 

cabezon

Sculpin Enterprises
WFF Supporter
Hi Steve-

I suspect the mayfly female subimago to be of genus Paraleptophlebia, but might be wrong. ;)
Hi Taxon (and tkww),
From the pictures of Paraleptophlebia that I have seen, the limbs are slender. This dun has beefy limbs. TKWW has suggested Drunella and the pictures that I have of that genus (especially nymphs) have weight-lifter limbs, not surprising in a crawler species. Which characteristics would you need to see in an adult to distinguish between these two genera? Of course, for my purposes - inducing a trout to strike a dry fly, the name is not critical, but I'm curious.
Thank you both for adding your expertise.
Steve
 

Troutnut

Active Member
I have to agree with those saying the mayfly is Drunella, although cornuta is an Eastern species. The beefy body just screams Drunella. A close relative, Timpanoga hecuba, has a similar body profile, but yours seems pretty distinctly olive and those are a bit more brownish in the pictures I've seen. I've unfortunately never found one of their duns to photograph.

A female dun is the hardest thing to identify to species, but I think the big-name Drunellas--grandis and doddsii--have hatched out from most places already. By abundance and timing, coloradensis and flavilinea could still be around. The colors don't look exactly like the male coloradensis I photographed recently (http://www.troutnut.com/specimen/1189), although that can vary by locale. I haven't photographed a good flav done either, but I think they're supposed to be pretty similar. However, colors on duns can vary a lot by location within that family of mayflies, so it's hard to say. It's also possible that this is one of the more obscure Drunella species like pelosa or spinifera.

The stonefly looks to me like the family Perlidae but I couldn't formally key it out from that picture... just the general body shape looks right. It's a male, and they sometimes have stunted wings.
 

cabezon

Sculpin Enterprises
WFF Supporter
I have to agree with those saying the mayfly is Drunella, although cornuta is an Eastern species. The beefy body just screams Drunella.
The stonefly looks to me like the family Perlidae but I couldn't formally key it out from that picture...l.
Thank you for the detailed reply. If these pictures are of any use to you, I’m happy to send you the originals.
Steve
 

Support WFF | Remove the Ads

Support WFF by upgrading your account. Site supporters benefits include no ads and access to some additional features, few now, more in the works. Info

Latest posts

Top