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3. Brown Dun hatch/swarm time?

Has anyone else watched a Brown Dun hatch or swarm? If so, what time of day did you see it, and how long did it last?

I came upon a woodland swarm late this evening. I thought I saw mating occurring higher above the stream. This would mean that parthenogenesis is not necessarily happening in "my" stream. I watched for awhile, but got distracted (venomous snake). I hope to catch it (the hatch, not the snake) again tomorrow night and note the egg-laying behavior and possibly nab some male adults for science. There's a range of nymph ages, so I should be OK, weather permitting.

Hi Konchu,

Brown Duns are pretty insignificant on the streams that I've fished, but I'm curious to know how your collecting efforts turned out. Your question also set me to looking at male/female eye size differences in photographs of Ameletus nymphs. In the photos of browni, tertius, and some unidentified Western species, I can find male/female differences. (In the case of tertius, there was also a photo of a male dun reared from an identified nymph.) However, in photos of ludens (including Jason's) and a fairly long series of lineatus, I only see females. Did you happen to notice any eye size differences in the nymphs you looked at on your stream? I assume that ludens and lineatus are closely related, but is lineatus also known to be parthenogenetic? Just curious....

I found the swarm again, but I wound up concluding that nothing I found would be of interest here. By posting, I was hoping to gain some info to help me study the species that also might be of some biological benefit to someone trying to match that hatch.

We can discuss some of nitty gritty details of Ameletus eye morphology, etc., via PM (for a number of reasons).

Oh shoot. National security, again. Seriously, this is information that I would really like to see (hear, whatever), and I'd be willing to bet that I know at least one other individual who would as well.

Me too, Konchu. If we have threads for "Just Fishing for Trout," why can't we have them for serious discussions about entomology also? I don't always follow all the details, especially when Taxon starts talking dirty about gender (Sorry Roger, couldn't resist)--but I've learned a lot from those who know more about bugs than I do.

OK. I guess there's at least a handful of interested people and probably no reason to play cards so close to my chest. Plus my mood changed. :} WARNING: Someone with a PhD will be using latinized words. If you find this offensive, stop reading now!

First, the swarm turned out to be another species (of flat-headed mayflies) that probably came from some distance downstream. I felt like a bit of a doofus when I found this, but the thing swarmed at late dusk, and Ameletus was the only species of that size ready to emerge from my stream. Goes to show that you can't always match the hatch based on the nymphs that you find where you are standing.

Secondly, the eyes were mostly the same size among the larvae I checked out. My sample size was pretty small because I threw most back, knowing the species already. Sometimes a better way to sex them is to look at the posterior abdominal sternites. Often, you can see shapes that remind you of male or female.

Third, the male adult of lineatus is not known to me. I am not sure if ANYONE has ever seen it. Thus, lineatus is possibly a obligately parthenogenetic species. A couple of male adults of the closely related ludens (thus facultatively parthenogenetic) have been reported, but there are some questions about these among certain entomological circles. Further, there are those who consider the distinction between lineatus and ludens to be doubtful, but the two seem separable to me.

I am working to obtain additional molecular data to explore some of these issues.

Thank you very much for answering my questions, Konchu. Although some might think this has little to do with fly fishing, I've already found an interesting (if circuitous) connection to this discussion. Investigation of information about other mayfly parthenogens led me to mention of a parthenogenetic Serratella species discovered (by fly fishers) on the Frying Pan in CO. This species displays abdominal bursting in the (female) dun. I don't know if I'll ever get to fish the Pan during the time of this Serratella emergence, but I'd relish tying (and fishing) an imitation of the "Gut-Busting Dun." :)

As an aside, I saw some of these when I was "up north". These female adults resemble something between Ephemerella tibialis (formerly in Serratella) and Matriella teresa (formerly in Serratella and Ephemerella).

Questions among certain circles? That sounds intriguing. Are they not convinced the males were fully male or something?

Just curious guys, is the offspring produced through parthenogenesis a genetic clone or are there individual specific traits?

Well, I'm not a geneticist, but my understanding is that it produces a clone. Mutations should still occur, meaning each one is a little bit different from its parent, but I think it would be comparable to the difference between identical twins... not usually noticeable.