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

> > Need help with id of a mayfly

DeaneJune 29th, 2010, 9:41 pm
Millsboro, PA

Posts: 2
I was fishing an evening hatch in late May of this year on the Driftwood Branch of Sinnemahoning Creek in Pennsylvania. There were Gray Foxes just finishing up for the day as the hatch weakened, Sulphers were coming off just at dark in growing numbers. The water temperature was around 68 degrees and the sun was bright, but behind the mountain and not directly on the water that I was fishing. A large mayfly had just hatched and flew right in front of me. I had seen this bug about five years ago and was not able to id it at that time either. I was able to catch it as it dipped back down. This mayfly has a reddish orange body with yellow segmentation when viewed from above. Turning it over, the belly is solid cream color. The wings are yellow with red veins and there are smaller wings, also yellow. There were two yellow tails about 1 1/2 times the length of the entire bug. The legs were also yellow but a creamy yellow.The thorax is yellow. I tied some to fish with on a size 12, 2X long hook, and it matched perfectly. I would be very appreciative for any help. I have looked all over the web and can't find a picture of this bug. I took a few with my camera, but I am a lot better fisherman that I am a photographer.
This is my first post. Thanks for the help.
GONZOJune 30th, 2010, 9:29 am
Site Editor
"Bear Swamp," PA

Posts: 1681
Welcome! Sounds like Stenacron, Deane. Did it look something like these?
(Keep in mind that the markings probably would not be as dark in your freshly hatched mayfly as they are in these "aged" specimens.)
DeaneJune 30th, 2010, 11:04 am
Millsboro, PA

Posts: 2
That is the bug. Thanks so much for taking the time to respond. Most cahills that I fish over are marked like small march browns. I know that the bug just hatched so it was definately a subimago. Are the cahill females marked differently than the males? I tie and fish size 14 cahills. This bug was a #12. The bugs in the pictures are all about an inch long which is about a 12, 2X long hook give or take a little. Maybe I should adjust my thinking and tie some longer cahills. Thanks again for the help.
GONZOJune 30th, 2010, 12:35 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Are the cahill females marked differently than the males?
Many species in several genera (including Stenacron and Maccaffertium) are commonly called "Cahills." The difference in markings between male and female is usually fairly slight, but the underlying eggs of the Stenacron females give their bodies a pinkish or orangish cast in both dun and spinner (often yellowish in female Maccaffertium "Cahills"). Aside from this body-color difference, eye size (male eyes are much larger) and body size (males are slightly smaller) are probably the most noticeable male/female distinctions in the duns. Here are a couple of male Stenacron duns:
(The last photo was probably taken closer to emergence.)

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: cahills
In the Mayfly Genus Stenacron by LittleJ
8Dec 1, 2006
by Troutnut
Re: Help with this bug please!
In the Identify This! Board by Shakeyfly
13Jun 7, 2010
by Brookyman
Re: light & dark cahill nymph patterns
In General Discussion by Lastchance
2Feb 18, 2008
by JAD
Re: stupid question
In Male Baetis bicaudatus Mayfly Nymph by Brian314
2Feb 27, 2022
by Brian314
Re: Delaware
In by Jesse
2Jun 30, 2011
Re: Gender
In Female Hesperophylax designatus Caddisfly Adult by JpMcKenzie
1Dec 16, 2017
by Creno
Not Stenacron, probably Leucrocuta
In Male Leucrocuta hebe Mayfly Spinner by GONZO
Re: Why mayflies dance
In General Discussion by Troutnut
5Dec 5, 2007
by Martinlf
Re: Paraleptophlebia mollis spinner
In General Discussion by Martinlf
4Jun 30, 2020
by Martinlf
Re: stages before emergence
In the Insect Order Ephemeroptera by Troutnabout
7Sep 18, 2006
by Troutnut
Most Recent Posts
Re: Are mayflies declining?
In General Discussion by Wiflyfisher (Adirman replied)