Jump to content
Fly Tying
troutracker

Plastronic Baetis-- Air Layer Covered Baetis Spinner

Recommended Posts

296466741_V4--imageforyoutubethumbnailwithscale1-23-25.thumb.jpg.5056553c29c579a5fd82b2528bbea7a9.jpg

 

Video of tying steps posted on Youtubehttps://youtu.be/G4DCul0VxQ8

 

The Biology behind the Plastronic Baetis

The Plastronic Baetis is my take on a silvery fly design that mimics the total reflection of daylight from an air layer, called a plastron, that a Baetis uses to respire as it crawls underwater to lay its eggs. The plastron is held between a spinner's upright wings and also covers its body. The total reflection from the surface of the plastron can obscure the spinner behind this mirror-like layer so that insect's details, like color and segmentation, need not be included in the fly design.

The idea of fishing flashy downwing wet flies as well as low riding or flat-wing spinner patterns after Baetis hatches has been around for decades. After reading several books that mention egg-laying Baetis it seems that my all-silver design is a bit different and perhaps new in that it uses the slot of a silver bead mounted facing forward on the hook to support a single upright silver tinsel wing as well as form the shiny thorax of a Baetis when underwater. In any case, over the past year it has proven to be useful fly after Baetis hatches as the look of the fly is new to the trout and they seem to take it readily.

According to Knopp and Cormier (in their book "Mayflies", 1997, Ch. 3), its the larger-size blue wing olives (BWO's, AKA Baetis) of North America-- those mostly size 20 and larger—that use a plastron to respire while they crawl to the stream bottom to deposit their eggs. An exception in the Baetis clan is the so-called tiny BWO's—those species usually much smaller than size 20-- that lay eggs on the surface like most other mayflies-- not underwater.

So, these larger size Baetis, made buoyant by the plastron, have a hard time clinging to the bottom, and often drift off (Ralph Cutter, 2005, "Fish Food" p. 81). Trout are known to eat these plastron-coated upwing spinners while they are drifting as well as when they crawl along underwater. If drifting, their buoyancy tends to make them drift up to the underside of the film: see the review in Peter Hayes 2013 book "Fly Fishing Outside the Box", Ch. 16.

A Baetis submerger ranks near the top of important trout foods for fly fishers to imitate. These larger Baetis are widely found throughout the world, can hatch a new generation every few months and are often the first and last mayfly hatch of the year. The underwater egg-laying phase of these larger BWO's includes at least half the hatch, that is all females (as well as some males!), try to end up as submergers back underwater. The Plastronic Baetis is a submerger pattern targets the aftermath of this egg-laying—a spent spinner rise if you will—as they release from the steam bottom and drift up. For anglers, this Baetis rise means hundreds to thousands of silvery air-coated spinners drifting down a stream usually starting in the later afternoon.

What is a Submerger? A working definition is that its a fully-functional adult aquatic insect that during the flying/terrestrial phase of its life cycle has on its own, or by act of nature, returned underwater. The point is that high-functioning adult aquatic-insects often end up back underwater as potential trout food. The reason for defining a submerger category of insect activity is that gives a name to a trout-food niche that anglers can target with appropriately-designed wet flies, not surprisingly called...submergers.

When tying submergers, the design constraint that fully emerged adults should be floating above the surface is gone opening up a whole new vista of dry-fly-like design possibilities using materials that instead sink-- including beads or metal wire on, say, a mayfly dun or spinner pattern. A side perk to fishing submergers is that there is no need to keep drying and treating a fly to keep it afloat!

To become a submerger, the aquatic insects have to pass back through the surface film (AKA film or surface tension). In nature, this feat can be difficult aquatic insects to accomplish (See review by Peter Hayes & Don Stazicker in their 2023 Kindle Book "The Flies That Trout Prefer"). Other than the larger Baetis species who en masse crawl underwater, other examples of insects that commonly become submergers and are also important to anglers are: some species of caddis, midges, damselflies, dragonflies, and aquatic beetles. Of course, any adult insect near the water can be swept under to become a submerger though usually they may not do so in enough numbers to get selectively targeted by the trout.

The difficulty of getting back under the surface film may be decreasing. Scientific research, as well as a common human experience, suggests that man-made surfactants, that act to reduce surface tension, may ease the way for an aquatic insect to get back underwater. Naturally occurring surfactants are also in play here. The man-made surfactants include the so-called forever chemicals, PFAS, that are used to make fire-fighting foams—resist breaking down and tend to accumulate in ever increasing amounts in streams. Over time, this build-up of PFAS, other man-made surfactants, as well as naturally occurring ones, would seemingly make it increasingly easier for an adult insect to simply sink back through the film or be taken underwater in riffles and such. Anglers may need to adapt new flies and strategies to reflect a trend of increasing numbers of submergers. Such adults would be imitated by a weighted upwing mayfly, like a Plastronic Baetis discussed next or a downwing Blue-Wing Midge pattern (https://youtu.be/uQhpxvoJ-fk) as well as many other fly patterns.

________________

Plastronic Baetis Recipe:

Hook: Tiemco 206BL sized 16-20

Thread: SemperFli White 20D Nanosilk

Thorax: represented by a 1.5mm slotted silver tungsten bead. NOTE: Slide bead onto the hook with the slot side facing towards the hook eye and leave it loose near the hook bend. Tie in the thread at the hook eye.

Single Upright Wing: Two strands of silver Hedron Fire-Fly tinsel are repeatedly folded over to make 8 or more segments. The mid-point of the stack of tinsel segments is then lashed on the top of the hook shank about 1/3 of the way back from the hook eye. The bead is slid forward and rotated so the uplifted wing segments can slide into the bead's slot. Secure the bead using tapered wraps of thread on both sides of the bead to build up the thorax. Continue to lash in the wing and force it up and into the bead slot using Figure-8 style wraps over and across the wing in the bead. Trim the wing to about 1.5 times the length of the hook shank as well as cut it at a steep angle towards the rear of the fly like an upwing Baetis. Finally, if needed, I trim off any flared tinsel bits that don't lie over the hook shank and are outside of the narrow single upwing form that I'm looking for.

Single Tail: I use a bundle of about four silvery fibers from a Coq de Leon feather. Set the tail length at least two times the hook shank length (Sylvester Nemes, "Spinners" p. 128). It is not necessary to flare the tails: Frank Sawyer ("Nymphs and the Trout", 1958, p. 84) first wrote that Baetis spinner tails are seen to merge together and form a single-looking tail as they crawl underwater. Once on bottom, however, the spinner tails may reopen to a V (Cutter, 2005,"Fish Food", p. 80)

Abdomen and Head: I now use Sulky metallic silver tinsel #8001 instead of the midge tinsel mentioned in the video. After winding a single layer of the tinsel over the hook shank and clinching it with the thread behind the hook eye, I reinforce it by coating it with a thin layer of Solarez bone dry UV cement. Sagging excess cement is then removed with a toothpick before curing the resin with a UV light. If an extra heavy and durable body is needed, use thin silver wire wound side by side up the hook shank from the bend and looped under the thorax bead to the hook eye and clinch it there with the tying thread.

Collar: a few light-dun CDC puff fibers

Whip finish but I use no cement as it tends to wick into the CDC collar

______________________

Fishing the Plastronic Baetis during a rise of the spent Baetis egg-layers.

To summarize the Plastronic Baetis video: the larger-size Baetis (hook size 16-20) crawling underwater to lay eggs are made buoyant by a gas layer, called a plastron, making it hard for them to remain on the stream bottom and easy for them to drift off—especially after completing the egg-laying part of their life cycle as they are nearly spent. Once they are drifting, their buoyancy tends to make them rise up to the underside of the surface film—a Baetis spinner rise—rather than a spinner fall typical of other mayfly species.

That said, in the riffled streams and pocket water that I fish, the turbulence often seems to mix the buoyant plastron-bearing Baetis throughout the water column rather than them gathering near the water surface. So, I fish the Plastronic Baetis by tying it in as a dropper on the short fine tippet tied to a micro-swivel in a two-fly rig attached to a Euro-nymphing setup. I add an anchor fly to the point of this rig so, after casting upstream, I can dunk the anchor fly down far enough to assure that the dropper fly is also underwater.  During this presentation, I use the micro-swivel as a depth marker so when it just emerges from the water, I know that the dropper fly is just underwater on the short tippet. I then lift the rig up while it is drifting so that Plastronic Baetis is near the level of the feeding fish—which can be just under the surface film. If I can see a feeding fish—that is one seemingly moving to and fro to intercept items underwater—I will cast directly upstream of that trout and then lift the fly so that the trout sees it rising up during the drift...and I strike if I detect a twitch of the leader or by the action of the fish it appears to have taken the fly. 

 

 

 

Share this post


Link to post
Share on other sites
3 hours ago, flyflinger said:

Wow! This is a very complete, detailed, and well-referenced write up.  Thank you! 

Regards,

 

I appreciate your feedback.  I think that given there are so many patterns out there that  if you post a new one you have to develop the back story and biology of the trout food niche you are targeting.  I also want acknowledge and thank those who contributed the video clips and still images that made the back story imaginable: Stuart Crofts, Peter Hayes, Don Stazicker and the Stroud Water Research Center.

Share this post


Link to post
Share on other sites

I really enjoyed that, and learned a new word even besides leaning a new way to fish the baetis hatch! Thanks for all that hard work, really pays off

Share this post


Link to post
Share on other sites
On 1/21/2025 at 10:59 AM, chugbug27 said:

I really enjoyed that, and learned a new word even besides leaning a new way to fish the baetis hatch! Thanks for all that hard work, really pays off

Thanks for the feedback!. I also learn a lot making the introduction for the video. In particular, the images and biology laid out in the introduction show me how the fly should look and how to fish it as well. Then the fun part of it is trying it out in a stream. I fish waters that see heavy pressure from anglers year-around--(as you likely know there are no fishing seasons here in Colorado). When angling for such pressured fish, I find that if I can come up with a new look in a fly that is designed to address a given fish food niche, then initially the trout seem to eat that fly eagerly—at least they take the fly eagerly for a while and, then at some point, seem to become conditioned to avoid it—compelling me to start using yet another pattern for this food niche. So, usually for continuing fishing success, I need to be able to use a sequence of patterns that address a given food niche.  

Share this post


Link to post
Share on other sites

On your point, Peter Hayes and Dan Stazicker have a theory to tie fly patterns in non-identical fashion to better imitate the uniqueness of the flies they are matching... From their e-book, Flies that Trout Prefer:

Screenshot_20250123-180145.png.95f0568299df56b45a4f7ea50b6c33f1.png

After displaying a batch of beautiful, identically tied flies...

Screenshot_20250123-180355.png.3942e2ebe0b333dc4222a644157000cf.png

Share this post


Link to post
Share on other sites
On 1/23/2025 at 5:09 PM, chugbug27 said:

On your point, Peter Hayes and Dan Stazicker have a theory to tie fly patterns in non-identical fashion to better imitate the uniqueness of the flies they are matching... From their e-book, Flies that Trout Prefer:

As always I appreciate feedback on the flies that I post. It allows me to expand on what I have said and attempt to clear up muddled writing on my part. 

My impression is that Chugbug27 brought up Hayes and Stazicker's (2023 Kindle Book "The Flies That Trout Prefer") idea of varying the look within a single fly design-- is because its an another approach to bypass a trout's conditioned avoidance response to flies it has hooked up with in the past.  

My way around a trout's avoidance response is a traditional approach: studying an aquatic insect's lifestyle, as well as its look and feel, to develop a new fly design that coupled with the proper presentation—also indicated by the insects lifestyle--to target a fish food niche. In this thread, the new fly is the Plastronic Baetis, a Baetis spinner crawling underwater to lay eggs and its drifting up in the aftermath.

I suppose that the purpose-built diverse fly look that H&S advocate is founded on the traditional flyfishing anecdote that says as the trout repeatedly eat a fly it becomes increasing chewed up and ragged—that is takes on a more diverse casualty look—and consequently the trout seemingly take that ABC fly (already been chewed, that is) even more readily. 

Still Hayes and Stazicker (H&S) make a good point: that you can make a diverse fly at the vise rather than wait for the fish to chew it up.  The thing is, I am so ham-handed and messy when tying flies, I seem to have been channeling Hayes and Stazicker's advice to vary fly-ties to get more strikes!  

Besides tying diverse variations of a single fly design like H&S advocate or developing a new fly design like I prefer to do (and clearly H&S like new flies as well), there's another traditional way to overcome a trout's conditioned response to not biting that same ol' fly—Rest the Fish. Being mostly a catch and release flyfisher I do not consider killing the fish as another way to eliminate the conditioning leading to an avoidance response.

Resting a fish means pausing fishing for minutes on up to months-long pauses caused by winter ice cover or imposed by closing the fishing season. Resting the fish is also well-known, time-tested and certainly effective way to overcome avoidance response of trout—whose downside is—you have to have the time to do so. 

So my real-time, tradition and science based approach to deal with the trout's avoidance response is to develop diverse fly designs that target a given fish food niche. If needed, after assessing what is happening on the stream that day, I sequentially swap in a these new-look flies and, if needed, fish them with different presentations till I get results or, shut-out, give it up for the day and go have a beer.

Share this post


Link to post
Share on other sites
On 1/23/2025 at 5:09 PM, chugbug27 said:

Anyway, I really like your work, I hope you keep going with it!

Thanks I appreciate your encouragement.  I learn so much by studying an insect to control how to design a new fly pattern, so I will continue to post new threads

Share this post


Link to post
Share on other sites

Excellent info and definitely ideas I need to work on! We have bwo’s all summer, I do not see dry fly eats but I know they are feeding below the film on them. Thank you!

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...