Baetis nymph? Mifflin Co.



Active member
Sep 18, 2006
Milroy PA
Seen yesterday February 21, 2022 Mifflin County. Hoping the pic will load.
Pic did not load. Sorry about that. I need to figure this out.
Trying again
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I'm not so sure. AFIK, most Baetis nymphs have either only two tails, or have a middle tail that is much smaller than the two outer ones.

Not an expert -- you could be right.
Thanks guys. According to Bam’s link some Baetis have three tails. I’m not saying it’s definitely Baetis, but we can’t rule it out. These critters were about a size 14 and good swimmers. Hare’s Lug and Plover would make a good imitation. Or GRHE.
I suck at identifying nymphs. Has the right body shape for a Baetis nymph, not sure on size. It's rather large for Baetis, which typically max out at 18ish.

It might be an ISO.
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Pcray. Thanks for jumping in. Most of the pics of Isonychias I have seen show a pale strip down the back, and a uniform body width from thorax to abdomen ( ie, no pinch point between the two). Plus Isos emerge in summer, so I guess their nymphs would be quite small this time of year. I don’t know this for fact, just a surmise.
Well, it's a swimmer nymph, which includes Baetis and Iso's. Fairly similar body shape between the two, and they get "fatter" (which would mean more uniform) as they get older and go through various instars.

As for coloration, it varies a lot based on which instar. Most Baetis nymphs I've seen have 2 lines, or dots. Yours has one broken line. But in addition to which instar, there are sooooo many Baetis species I hate to base it on that.

Time of year, you have a point. More likely to see Baetis right now. Though obviously ISO's are down there, just much farther from emergence and less active. My comment was more based on size. You indicated it was a 14ish. I'm not sure I know of any Baetis that get much bigger than an 18, maybe a 16 in some waters. That's the only thing that gave me pause to say Baetis. Where as for an ISO, that's rather small, which makes sense since he still would have a lot of growing to do...

So super big Baetis, fully mature and ready to pop, larger than most specimens? Or immature ISO? Or something else? I don't know. It's a swimmer nymph, confident in that! lol.
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All good comments pcray. It could easily be a 16. We recently had a flood with the rain and runoff. These nymphs were stranded in a shallow pool on the floodplain. This steam is a limestoner with some aquatic moss along the margins, which is good Baetis habitat I believe. I do see 16 adult Olives in spring on this stream. I took the pic through the water surface and have no direct size reference, so relying on memory. I was very surprised at their mobility. Thought they might be shrimps at first until I got a closer look.
Also size 18 black needle flies (stoneflies) were out and about as well as a size 12 black stonefly. Will post a pic of the big black one soon. I love that we can now post phone pics here. Much improved.
I honestly think it’s a Blue Quill nymph. The size 14 would match that bug, three tails and the gills on the sides of the abdomen are characteristic of that species of mayfly.
Dc410. Good call. Blue quill, Neoleptophlebia adoptive or something related. That makes a lot of sense. I’ll be on the lookout in April for the adults and get some pics. The trout nut website seems to agree. Thank you.
The blue quill hatch is one that has never gotten a whole lot of press. Now that the PA trout opener is the first Saturday in April (April 2 this year) you should be able to hit some decent blue quill hatches in the early afternoon on many of PA’s trout stocked fisheries. I can remember several times over the years getting into some great dry fly action on the afternoon of opening day in northern PA on some fairly big streams like Pine Creek. Some of these hatches occurred on very cold, overcast days even in the middle of a snow squall. A good blue quill hatch can turn the trout on like a light switch.