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This topic is about the Mayfly Family Baetidae

"These little critters supplant the importance of many other well-known mayfly hatches."

-Fred Arbona in Mayflies, the Angler, and the Trout

Arbona did not overestimate these critters. Their great numbers and multiple broods each season make up for their size, which is rarely larger than size 16 and often smaller than size 20.

Hardly mentioned in angling literature prior to the middle of the last century, baetids have become increasingly important to anglers, rivaling any other family of mayflies in this regard. This is largely due to the extension of fishing seasons that now include the early and late periods when this family’s species usually dominate hatching activity. Another important reason is the tremendous improvement in tackle allowing more practical imitation of these little mayflies. The dramatic ecological changes in many of our watersheds and the subsequent impact this has had on the makeup of taxa populations is also a factor.

Taxonomically speaking, this is a most unruly family. The entomological community seems to be perpetually reclassifying its genera and species to the chagrin of many anglers. These changes are not capricious. The reason is older nomenclatures haven't provided the taxonomic flexibility required as more becomes known about the complexities of baetid relationships. Classification of this family’s genera and species is very much a work in progress. The changes have been so extensive that it is beyond the scope of this hatch page to track the taxonomic history effectively without interjecting even more confusion. If you are frustrated by the inability to find some of the old familiar names, you're not alone. Rest assured these popular hatches are listed here, just under the latest classifications. The old famous names are referenced in their hatch pages.

Common baetid hatches with a national distribution are the species Acentrella turbida, Baetis brunneicolor, and Baetis tricaudatus. In the West, Baetis bicaudatus, Diphetor hageni and Plauditus punctiventris can also be common. In the East and the Midwest, look for Baetis intercalaris and Plauditus dubius. The species Iswaeon anoka is important in both the West and Midwest. Some of the Procloeon and Anafroptilum (prev. Centroptilum) species are coming to the increasing notice of anglers across the country.

Stillwater anglers are likely to run across Callibaetis ferrugineus ferrugineus in the East and Midwest. Western anglers will find Callibaetis californicus and Callibaetis ferrugineus hageni to be very important.

Streamside identification of these mayflies to specific and often even generic level has always been difficult. This is now even more so as new taxonomic evidence has shown hind wing conformation (or lack of hind wings) and other features are less dependable as ways to tell the genera apart. Many of the lesser-known species probably produce excellent local hatches but have not caught enough attention to be properly recognized by anglers. The lesson is that we should not assume anything about the identity of many Baetidae hatches we come across; they may not even be in the Baetis genus, let alone familiar species. Read more...

There are 94 more specimens...

The Discussion

DryflyJune 16th, 2010, 12:51 pm
rochester mn

Posts: 133
I was out the other day fishing in a steady rain. Things were slow until the bwos starting coming off. Why do bwos hatch is such crappy weather?

Possible disadvantages, would be takes longer to dry wings, exposing them to predation longer. More cripples.

Possible advantages, could be they won't dry out cause its wet and cool out.

TaxonJune 16th, 2010, 4:37 pm
Site Editor
Plano, TX

Posts: 1311

Winged mayflies are unable to take in water. Some Baetid species may have evolved to emerge on low-light (crappy weather) days, thereby lessening their vulnerability to excessive dehydration. Other ideas?
Best regards,
Roger Rohrbeck
DryflyJune 16th, 2010, 9:58 pm
rochester mn

Posts: 133
Thats what I was thinking too, but other mayflies like sulfers love hot days.

So maybe just baetids have this avoiding dessication thing figured out.
TaxonJune 16th, 2010, 11:18 pm
Site Editor
Plano, TX

Posts: 1311

Each species has evolved with those characteristics and behaviors, which (over time) have most favored survival of that species. And, given the amount of time that mayflies have been around, they must have encountered environmental conditions very different from what we see today. So, perhaps that particular emergence behavior evolved as a result of one of those environmental conditions, but because the behavior is currently evolution-neutral, they are stuck with it until it is no longer evolution-neutral. Or, so it seems to me.
Best regards,
Roger Rohrbeck
OldredbarnJune 17th, 2010, 9:31 am
Novi, MI

Posts: 2600

I know we have all heard the angler's version of the "old-wives tale" when it comes to Baetis and bad weather...I have seen enough evidence over the years to want to believe it's true myself, but I think we need to be a little cautious though continuing to pass something on that may not be totally true.

I am more inclined to think that these little buggers are so prolific and have so many related cousins of similar size and color that it may be a good bet to carry their imitations always. Think "Hidden Hatch" here.

Example one: This supports the ugly weather belief...Several Mays ago I floated the South Branch of the Au Sable with a friend when it hailed on us during our float. We had to take cover under some cedars. I had a bag of ice "cooling" our beer that never melted after a whole day on the stream...The only hatching flies, almost the whole day, were what I call Baetis dinkus or Baetis dinky...I think they were once called cingulatus...

There were these little floating sailboats all over the water and they never seemed to lift-off...Just floated along for the most part, little wings erect, and unfortunately unmolested by the trout.

Example two: This spring, North Branch of Au Sable, the Friday before the last Saturday in April...It's unseasonably nice out...My little B. vagans now renamed were mixed in among Henny's, Little Black Caddis, Little Mahoganies etc...I took brook after brook on a size 18 Klinkhammer with a dark dun CDC post and dark dun hackle and a dark/natural goose biot wrapped abdomen...The thorax was dark olive/brown beaver instead of peacock...I couldn't see the damn thing! My inability to see it didn't hamper the trout one bit. (I know that the fish may have taken it for the P adoptiva's, but they weren't saying).

Example three: It was 2004 on the Gallatin inside the Park..A wonderful day with a few white puffy clouds a few days before Labor Day. I had the end of the PMD's hatching sporadically that I could see and trout feeding, but I could not catch any! I put my rod down and stared in to a deep bend and watched nice fish flashing and thought...Nymphing!

Before I swithched flies I left all my gear sitting on the bank and grabbed my little aquarium net and headed downstream. I waded in and facing upstream dipped my net in to the water and it came out crawling with tiny little Baetis!!! I had totally missed them! They had blended in so infuriatingly well!

I wish I had the pictures here to post of the fish I took thereafter...I caught this one Bow that I'll never forget...The river here isn't that big and I was fishing from the bank and he literally tore up the hole! He ran up and down and in to the air and was one of those rare fish that are so much fun you find you are laughing and talking to yourself and it as you unhook it and return it to the stream...That sort of success is what makes dry fly fishing what it is...I figured out the problem, fooled an old citizen of the stream, and he nearly kicked my ass in the process, but I was grinning ear to ear looking around hoping someone saw all this!!!

Anyway...I think if you decide to leave the Baetis box back in your room because it's going to be so nice out that day...It may be a mistake! Just my two-and-a-half cents...

In shear numbers, and I know we lump in several bugs under the Baetis umbrella, they are by far the most prolific, seen all season by trout, and over-looked many times by us poor-sighted anglers. Maybe it's not our poor eyesight that's the problem...These "Fisherman's Curse" are a pain in the you know what to fish and maybe we are "blocking Vito"...It would be easier to tie on a size 12/14 Henny and pretend we didn't see them.

"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
RleePJune 17th, 2010, 2:01 pm
NW PA - Pennsylvania's Glacial Pothole Wonderland

Posts: 398
I always wondered if maybe it had something to do with an instinctive behavior to emerge during periods when conditions were such that the potential for predation was minimized and potential for concealment was optimized. That maybe during periods of rain and high wind and all the other misery that often accompanies baetis hatches that there is something in the species perpetuation imperative coding that tells it NOW is the time to emerge what with all these weather related distractions going on around it.

I know that other small-brained creatures react this way. I've often seen trout streams come to life with rising fish when the surface is patterned with raindrops for example. Something there about not being seen from the fish's standpoint, I've always thought.

Then there was my Mother's brother Raymond, speaking of small-brained creatures. He devoted his life to seeing how long it would take to grow his liver to the size of a Cocker Spaniel, but he would never walk to the liquor store unless the weather was lousy. The way he figured, he had a better chance of not being seen. This turned out to be true as he got clipped by a bus on his way back from an ethanol run. Not hurt too bad. Just knocked on his arse and jostled his liver a bit.

Anyway, that's my theory...:)
MartinlfJune 17th, 2010, 3:10 pm
Palmyra PA

Posts: 3044
Spence, try a white poly yarn post on that little Klink. I've seen some of the most pressured fish I know of eat that fly with no qualms, and it's easier to see than the dun posted version. I have a few with orange and (OK no jokes here) pink posts for extreme glare. Black can work too, depending on the light. For the early season flies, at least, the fish don't seem to care a bit about what color post.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
OldredbarnJune 17th, 2010, 7:26 pm
Novi, MI

Posts: 2600

I usually use light dun Hi-Vis...I don't know what I was thinking...Maybe a Johnny Cash Fly?! Maybe we could call that pink one of yours a Pinky Klinky...:) Boy that's a stretch, eh?!

You know I had used the CDC feather tips and the scrap was like a little triangle...I know that this may be hard to picture...These little triangles were long enough for posts on this little fly...I matched two feathers and they looked sharp at the bench, but invisable on the stream.

Hans van Klinken meant the fly to represent caddis, but who knows what they were taking it for. Like I said I had Baetis, Paraleps, and the Little Black Caddis...It wasn't a bad choice in that situation and I'll just have to tell myself I was matching the hatch though I'm not sure which one...You just have to love wild Brookies! They can make an old dry-fly-guy almost look like he knows what he's doing!

"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
DryflyJune 17th, 2010, 8:06 pm
rochester mn

Posts: 133
I've always thought the post color didn't matter as the fish wouldn't see it. I've always used white Hi-vis, though I may tie tome others with pink or black posts, white doesn't work real well when there's lots of foam.
MartinlfJune 18th, 2010, 10:47 am
Palmyra PA

Posts: 3044
I use hi-vis on some of my parachutes, most often white/clear on Tricos. Poly yarn floats, and that's one reason I like it for the Klinks. But the brightest orange I have is calftail, so I typically use that--or I do have some antron (I think it is) in a red-orange that shows up in some parachute posts. And the pink is fluorescent pink hi-vis. So I do use all kinds of things. Some of my sulphurs find themselves floating along with a light dun poly-yarn post, which get fished when the light is right. For others it's white. For Isos I use dark dun poly-yarn. White might work there, but so far I haven't had any trouble seeing the Iso. When I can see it, I match the wing to the natural as best I can. When I have poly-yarn the right color, I use that. Hope this is helpful.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
GONZOJune 18th, 2010, 8:36 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
I know we have all heard the angler's version of the "old-wives tale" when it comes to Baetis and bad weather...I have seen enough evidence over the years to want to believe it's true myself, but I think we need to be a little cautious though continuing to pass something on that may not be totally true.

I think that Spence is right to raise a note of caution about this association. Although most of us have probably seen some great "crappy weather" BWO hatches, the notion that mature baetid nymphs wait around for lousy weather before emerging (for days or possibly even weeks?) seems pretty unlikely to me.

Why, then, do we associate baetid emergences with bad weather? I believe this is simply when many anglers are likely to notice them and have success fishing to them. During much of the late spring or summer, they usually hatch early in the morning or late in the evening, often causing them to go unnoticed (or, as Spence suggests, conveniently ignored). At such times, we may only notice the rises of trout to something unseen (Spence's "Hidden Hatch"). Cooler, overcast or "crappy" weather extends the emergence period through a greater part of the day. Because we often have more success fishing to them at such times, we may come to expect baetids only on bad weather days. During the cold weather of early spring or late fall, however, the best baetid hatches often occur around midday or early afternoon on warm, sunny days. Throughout the rest of the season, they hatch in good weather and in bad, just at different times of the day.

OK, I realize that my explanation might not be particularly popular, so try this: The next time you encounter one of those bad weather BWO hatches, go to the same spot at dark on the very next "normal" (hot) weather day, and stretch a seine across a prime drift for a while. Unless the emergence period of that particular species has come and gone, I'll bet that you'll probably find plenty of the same baetids, adults as well as nymphs.

If you are anything like me (read "old"), this will be an interesting but useless experiment. Fishing little #20 or smaller imitations after dark is not my favorite thing to do, so I will continue to look for those magical "crappy weather" BWO hatches. :)
DryflyJune 18th, 2010, 9:15 pm
rochester mn

Posts: 133
Gonzo is right about baetids hatching in nice weather. I remember one afternoon the fish were up rising consistently. I looked studied the water BWOs! I had no bwos with me. It was july or august, baetis aren't supposed to be hatching. I caught two on a cdc and deer.

The simplest explanation may be that since baetis emerge nearly nonstop, they are bound to emerge in crappy weather.
JADNovember 4th, 2010, 6:09 am
Alexandria Pa

Posts: 362
Hi All
I am reading through the posts that I missed this summer because of my job( fishing central Pa).I would like to reply to this post .
After fishing 57 days out of 60 and living on the river , I believe the Baetis Hatch is no more, it has left central Pa not to return. Or after some scientific investigation, they know when I am putting my waders on.
So next year I will ask Louis and Gonzo to verify my findings.

Is anybody out their.


They fasten red (crimson red) wool around a hook, and fix onto the wool two feathers which grow under a cock’s wattles, and which in colour are like wax.
Radcliffe's Fishing from the Earliest Times,
TaxonNovember 4th, 2010, 7:39 am
Site Editor
Plano, TX

Posts: 1311
Is anybody out their.

Nope, just us dogs. I suppose it might be possible, but for multiple species of Baetis, particularly those as common as B. intercalaris and B. tricaudatus, to (simply) vacate nearly 1/3 of the state of PA, without some truly catastrophic triggering event, sure seems unlikely to me. However, I'll be interested in hearing what others may respond.
Best regards,
Roger Rohrbeck
PaulRobertsNovember 4th, 2010, 8:25 am

Posts: 1776
Thanks for bringing this back up Roger. And thanks Spence and Lloyd for your contributions. (Loved your 'bow story too, Spence.) I was wondering about this very thing -if Baetids emerge early late or after dark, or throughout a brighter day -instead of consolidated into a "Baetis Hatch". There is rarely a day onstream I don't see Baetis duns in the air.

I was aware of this with the eastern PMDs (invaria/rotunda) -"tough hatch", for we and the trout it always seemed. Seems they like to emerge from turbulent riffs mid-morning. And they rarely seem to come off really dense, but continuously. I've never had great fishing around them and wondered if they'd found themselves a nifty little niche strategy that reduces predation by trout and birds. Along this line, I wonder if temporally well distributed Baetis emergences on nice days serve to reduce predation? There may be two strategies operating.
OldredbarnNovember 4th, 2010, 11:04 am
Novi, MI

Posts: 2600
I was aware of this with the eastern PMDs (invaria/rotunda) -"tough hatch", for we and the trout it always seemed. Seems they like to emerge from turbulent riffs mid-morning. And they rarely seem to come off really dense, but continuously.

I floated the South Branch Au Sable years back and we were just upstream a bit from a place called Daisey Bend...It seemed like we had rounded a bend and all of a sudden there were invaria absolutely everywhere...We had fish feeding in the bend up ahead and beached the Au Sable river boat...

We had bugs all over us and both myself and my guide friend had the rods going like crazy and had piss poor results...We could see fish flashing and I remember telling my friend they are hitting them before they made it to the surface and out came the emergers etc...Still poor results...

My friend, a big dry fly guide, decided to try something completely different over a nice fish and tied on a caddis and tossed it in there...He's pulling off these wonderful massive upstream mends and that fly is just sitting there right over this guys head and nothing!

Once the switch went off and it all came to a halt we were stunned on how few fish we had hooked during such a massive hatch...We got back to the boat and there were hundreds of flies all over it...I had to sweep them away to sit back down.

We should of been cleaning up and a good nymph angler would of been...No doubt!

"Even when my best efforts fail it's a satisfying challenge, and that, after all, is the essence of fly fishing." -Chauncy Lively

"Envy not the man who lives beside the river, but the man the river flows through." Joseph T Heywood
PaulRobertsNovember 4th, 2010, 11:59 am

Posts: 1776
Yeah, that sounds like it...except my streams were not of the Ausable's caliber. I tied and fished wets for that hatch, but never was able to give it a real fair shake -that's where I left it anyway. I ended up ignoring invaria much of the time as I felt there were better opportunities elsewhere.

E dorothea could be tough too, as the season progressed esp. It was partly due to water type, hatch density, and then timing later. The water could churn in the head riffs of pools and I'd mutter "dorothea". I caught fish on them though, unlike invaria. The western infrequens/inermis counterpart can also be tough because of density mostly I believe. I don't have much experience with them yet but have been there just enough to get the dorothea feel from them. Still learning. So many bugs so little time. Can't think of a better conundrum.
GutcutterNovember 4th, 2010, 2:16 pm

Posts: 470
very strange...
it would be interesting to know where you have been fishing in central penna. i have found fishable baetis hatches this year in march, april, may, july, (i was tarpon fishing in june) august, september and october fishing central, west central and north central spring creeks and freestones. other than tricos (my personal favorite) i have tied more baetis patterns this season than any other. some of 'em even worked - ha! now granted - they weren't always "blue winged" and some times maybe they had just a suggestion of "olive".
so that you don't think i am full of s#*t, on some (most) of these trips i was fishing with other forum members who would agree with me.
i understand what gonzo has previously stated on this thread, and i agree wholeheartedly. they weren't always hatching on badweather days. i usually can only fish weekends, so my choice of fishing days are scheduled well in advance. but, unlike gonzo, i'm one of those "old guys" who likes to fish small flies near or after dark...
john - you can PM me with the river you were on and i'll share with you as well.
All men who fish may in turn be divided into two parts: those who fish for trout and those who don't. Trout fishermen are a race apart: they are a dedicated crew- indolent, improvident, and quietly mad.

-Robert Traver, Trout Madness
LastchanceNovember 4th, 2010, 3:25 pm
Portage, PA

Posts: 437
I fished BWOs in Central, PA, with Gutcutter, but I won't tell you all of the places. Spring Creek, which everyone knows about, is one of those streams where we had a fishable hatch.

PS. I was out today expecting a great hatch with the rainy conditions and I never even saw an olive. Conversely, I've hooked some fish on BWO emergers and nymphs on a few sunny days the past 2 weeks. Thyere were fishable hatches on those days. Go figure. From what I've read and been taught cool, rainy days are supposed to provide perfect hatch conditions.
PaulRobertsNovember 4th, 2010, 5:10 pm

Posts: 1776
I've always assumed that humidity, or lack of it, is a key factor, but I've never looked into it. If you keep good records, this might be a good retrospective.

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