Mayfly Family Baetidae (Blue-Winged Olives)

Hi Jason! Do you have a picture of the (acentrella-miniature BWO nymph) on the site? I've been fishing them and wanted a better idea of how they look.
Thanks,
Bruce

In searching for nymphs in my small stream in northern Maryland, 500 yards from the PA line, I came across a 2 tailed mayfly that was not a of the Epeorus genus.

It was in a fast riffle section along with Epeorus nymphs. This was about 3/8� in overall length including tails. Darker straw coloration with dark brownish black wing cases that were pronounced in color and shape. Biggest factor was the tails. Median caudal filament was truncated, very small compared to the outer pair. Not even sure if tail/ caudal filament should be used to describe. In my books the closest thing is the Pseudocloeon futile. Which is an old taxonomic name I’m finding out.

This find seems rare in my area and experience. Hopefully I can get a photo...

every book/article I read says Baetidae is the most imporant family and Callibaetis the most important genus of mayfly. Why? Does this just mean they are the most prolific? Am I not likely to encounter any other family/genus on a western river?

I hosted two visiting delegates to the T.U. National Convention in Madison, WI. on September 25, 2013, taking them to the Big Green River in Grant County near Fennimore. There was a high overcast in the morning, and these mayflies [which I merely called "BWO's" and imitated with #16 parachute dries - thin olive bodies, gray wing posts and dun parachute hackle] - were active. Both of my guests raised browns fishing a gray nymph behind a #16 parachute dry BWO. As long as my flies catch fish, I don't need to be a detailed entomologist. Nevertheless, I do sincerely appreciate the detailed scientific info, because it helps me focus my flytying and fly selection. Thank you.

Often the first fishing for bug-eaters I do every year is the early Baetis activity. Then…the Baetid activity just continues through the year on virtually all the waters I fish. This is probably so for you all too.

I often fish a Baetid dry ahead of a Baetid nymph, since individual fish could be targeting either. I fish the #18 or #20 nymph on a short (~18-24”) length of 7x to the bend of the hook of a #16 Parachute dry. A tiny daub of tungsten putty helps the short fine dropper break the surface film, as it’s critical to have the dropper line as straight as possible as soon as possible so I can detect every take. I use this combination all year and it's even a smart prospecting rig on waters calm enough to see the small dry.

For my bread-n-butter recipes I can be a pretty lazy tier, so I want as close to an instant tie as I can get. The following are two ~4 minute recipes:

Parafilm Baetid:
This pattern uses a single section of mallard flank barbs (tinted ahead of time with a swipe of a permanent marker) for both the tail and the legs, using the tips for the tail and the butts for the legs. Parafilm (laboratory thermo-plastic film) is used for the body, and tinted with permanent markers. The Parafilm body makes the fly sink a little quicker than dubbed ones, esp with a heavy iron (like the 3906 in this pic).

It’s important to me to have the fly drift correctly in the water, not flip upside down. So it needs an ample tail to right the hook when it’s tethered. Also, with the Parafilm body it helps to adjust the legs with thread so they angle upwards, so they are above the central plane of the fly. I take the most time on this fly with the legs so they are equal on each side in number, length, thickness, and orientation. No need to be anatomically correct so two legs to a side is enough to suggest legs. I suspect the upside down or rolling flies affect my catch rate, as I’ve had repeated refusals to such flies and then made good by tying on a fresh one.


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(Yeah, I know there are 4 legs on the left side -I snipped off #3 after I noticed.)


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Baetid #2:
The second pattern is similar to a combination of the “WD40” and "Kimball's Emerger", except that it doesn’t bother with the wingcase. The wingcase is suggested with permanent markers: a spot of dark brown behind the head, and two black wing-buds. Again the tinted duck flank for tail and legs, then olive thread for the abdomen, a pale pinkish-golden dubbing for the thorax. Legs equal again, but not so critical that they ride well above the central (dorsal/ventral) plane, as the dubbing adds some buoyancy. The legs should not hang below the plane or the fly will likely ride upside down.


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{EDIT}: Just noticed this fly has the wingcase, but I usually just omit it.

I tie a few others too, but these cover the dropper nymph deal pretty well for me.

What Baetid nymph patterns do you rely on?