Fly Fisherman Throwback: John Gierach's Blue-winged Olives

From coast to coast, this foul-weather hatch greets the season and bids it adieu.

March 06, 2023 By John Gierach

Editor's note: Flyfisherman.com will periodically be posting articles written and published before the Internet, from the Fly Fisherman magazine print archives. The wit and wisdom from legendary fly-fishing writers like Ernest Schwiebert, Gary LaFontaine, Lefty Kreh, Robert Traver, Gary Borger, Joan & Lee Wulff, Dave Whitlock, Vince Marinaro, Rene Harrop, Doug Swisher & Carl Richards, Nick Lyons, and many more deserve a second life. These articles are reprinted here exactly as published in their day and may contain information, philosophies, or language that reveals a different time and age. This should be used for historical purposes only.

This article originally appeared in the December 1989 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Blue-Winged Olives."

There are days when a Blue-winged Olive hatch calls for a routine reality check. Quickly now, is it spring or is it fall? With Olive hatches it could be either, and if I was dropped through a time warp onto a good trout stream during an Olive emergence (and I'll admit that's how I feel, some days), that's the first question I'd ask if there was anyone around.

Ideal Blue-winged Olive weather is the kind that comes with the large, symmetrical movements of changing seasons. Around here, in Colorado, it can be in April and again in October, or maybe March and November if there's more than a whiff of snow in the air. It's invigorating to be out in this weather and, sometimes for me, a little disorienting, too. It's the only hatch I'm familiar with that comes off equally well twice a year, at the beginning and the end of the fishing season. Sometimes fishing Olive hatches gives me the feeling that time keeps circling back on itself, and the same things keep happening again and again. That may or may not be just a convincing illusion.

I'm part of that fairly large school of fishermen who call the mayfly in question a Blue-winged Olive, but you often hear it referred to as a Baetis by those who are striving for entomological correctness. It works either way for me, but you must be somewhat careful of this accuracy business.

Which Bug Is It?

Most fly fishermen equate Blue-winged Olives with Baetis mayflies. A Baetis is a common small mayfly–about a size 16 or 18–that lives in cold trout streams, and it has a distinctive gray-olive body and slate-blue wings that give it its common name.

Fine, but at least once every spring and fall I hear someone say, "Yeah, there was a big Baetis and a little one, about a size 22, and the damned fish wanted the small one." I used to say that myself until someone took me aside and informed me that, in this particular case, the little Baetis was actually a Pseudocloeon.

But if you consult a bug book on that one, you'll find that the Blue-winged Olive mayfly in size 22 or smaller could actually be the Pseudocloeon, Cloeon, or the Neocloeon. In Hatches Caucci and Nastasi take these flies as a group and list the ten "more important" species, noting that some of the even more "remote" bugs may be what you're fishing to on some rivers. To their credit, the authors leave it to the reader to decide the importance of that possibility.

The size 16 or 18 Blue-winged Olive that appears twice or even three times a year on the same water is probably some kind of Baetis, because these insects have multiple broods. Still, bug watchers who know tell me that at any given time you could be looking at early or late hatches of one of the many other mayflies also known to some as Blue-winged Olives, like the Paraleptophlebia adoptiva (a.k.a. Blue Quill), a couple of Ephemerella species and ... well, you get the picture. According to Caucci and Nastasi, there are 20 different mayflies that are called Blue-winged Olives by at least some fishermen.

A large rainbow trout in a net on a rock, with fly rod and reel above. — A rainbow from Colorado's Frying Pan River fell for the author's fly on a typical Blue-winged Olive day … cool, overcast, and drizzly. (John Gierach photo)

With all that in mind, I've backed away from using the little Latin I know, and instead I use the traditional fly names, which are accurate enough for most of us. A Blue-winged Olive is a small mayfly with bluish wings and an olive body that hatches in the spring and fall–and there can be big ones and little ones. If you use imprecise language, you're less likely to be wrong.

Finding the Hatch

Here in northern Colorado, Blue-winged Olives come off as predictably as any hatch in the West. In the tailwater rivers-those spring-creek-like numbers where the water temperatures stay more or less regular through the seasons-Olives begin appearing sometime from mid to late March or early April, sometimes lasting into May. On undammed rivers and streams the dates slide around more, but I usually see the Olives before the stream flows start pumping up for the runoff and while the weather is still brisk. These Olive hatches are often preceded by some midges, but they still qualify as the first dependable dry-fly fishing of the season.

And then it happens all over again in the·fall, usually in October or November, when the major mayfly hatches are pretty much gone and you're not likely to see a caddis again until the following summer.

Some winters, as friends and I have slogged around on the tailwaters trying to get over bad cases of cabin fever, we've stumbled upon the mysterious third Blue-winged Olive hatch that some of the bug books talk about. This hasn't happened often, but it's always been in January or February when the sight of mayflies can really brighten up your day, even if the trout are a little slow to take them.

My guess, based on haphazard local observation, is that the third generation lives in the tailwaters, but not in the colder freestone streams where the winters are harsh.

The hatches, even the midwinter ones, tend to be in the afternoon, and the bugs have a taste for gray, nasty weather. So much so that high atmospheric pressure and bright sun can cancel a hatch, though it's more likely to just reduce the number of insects and the hatch duration.

It's one of those neat fits you sometimes find in both sport and nature: The nasty weather keeps the insects on the water longer before their wings dry so they can fly away, making them easier for the trout to eat. And trout, of course, feel more confident about rising to the surface under the low light of an overcast sky. A good deal of heavy-duty predation goes on during an Olive hatch, and the bugs seem to have compensated for this by arranging it so that they emerge in large numbers. The result is often lots of trout rising confidently to a thick hatch. It's the kind of thing you read about in fishing magazines.

Luckily, spring and fall in the Rocky Mountains bring waves of drizzly cold fronts, and several times a year I find myself patiently explaining to incredulous nonangling friends that it's actually the smart fisherman who's out there freezing his butt off in the rain.

Olive Fly Patterns

The Blue-Winged Olive is found in many trout streams around the country, so it has received a great deal of attention from fly tiers over the years. The standard Olive pattern (if such a thing still exists these days) is the traditional hackled dry fly with dun tail, hackle, and wings, and a dubbed body the color of which no two writers have ever described with the same words. That comes partly from the usual idiosyncrasies of writers and fly tiers, but also owes to the fact that there are some variations in coloring from one stream to another.

Fine points aside, if you dub a body of creamy, grayish-olive rabbit fur, you won't go far wrong. A store bought Green Drake is usually greener, while a Blue Dun is grayer. And remember that any dubbed fly will darken a little when you grease it up with floatant.

A pseudocloeon mayfly on a dark background. — The *Pseudocloeon*, mistakenly called a "little *Baetis*" by some, is about a size 22. (Ted Fauceglia photo)

Two quill-bodied patterns, the old Blue Quill and the newer Olive Dun Quill, are popular around here among fishermen who want a hackled Blue-winged Olive pattern with a segmented body and a finer silhouette. The two flies are very similar, except that the latter uses a stripped quill that's been dyed a dusky olive dun.

I've come to think of the hackled patterns as fastwater flies for conditions where you need some fairly serious flotation, and where the trout get into that aggressive eat-'em-beforethey-get-away mode–like on a small, freestone creek That's because I do most of my Blue-winged Olive chasing on special-regulation waters where the fish have been trained to want something a little more accurate.

I don't think that's unusual. It seems to me that Blue-winged Olives are often found in rich, healthy streams along with lots of other bugs: the kind of streams that grow good-size trout, attract more than their share of fishermen, eventually come under some kind of special restrictions, and end up being known as difficult or "technical" waters.

I like the Swisher/Richards-style No hackle Dun, which I still think of as a newfangled pattern even though it's been around for a coon's age now and is pretty much of a standard. It's a simple, uncluttered fly that a lot of trout will take after having only glanced at a hackled pattern.

It's one of several "switch-to" flies, as in "Well, that didn't work, what are you gonna switch to now?" Others include the right size and color Paradun, Thorax Dun, Iwamasa Dun, and God knows what else. Consult your local fly shop on that.

Lately I've done well with some variations of a trailing husk Blue-winged Olive emerger. One of these flies consists of the front two-thirds of a Nohackle Dun (divided hen-tip wings and an olive body) with a trailing nymphal shuck made from a whole, small hackle feather, a strip of ostrich herl, or a little snippet of marabou hanging off the back.

Another pattern is the same fly except with the wings cocked back a little, and two turns of hackle for legs.

Yet another is the same fly again, but with a half-emerged wing made of rolled poly yarn.

And so on.

During the last Blue-winged Olive hatch on the South Platte River, one or another of these flies really hammered some of those hard-bitten, catch-andrelease-area rainbows who thought they'd seen everything. That's not because I'm such a great fisherman, but because I finally came to understand the meaning of a single piece of negative information. Namely, that through all the haggling over Bluewinged Olive patterns for the South Platte hatches, I'd never heard anyone mention trailing husk emergers. I figured it was worth a try, and it was.

That hatch lasted a long time, and I put a lot of miles on the truck, driving to and from the river. (Fly-pattern research and development takes a good deal of time, you understand.) I missed the last week or so of the hatch, because even though time flows in a circle, a guy does have to make a living. And you don't have to catch every fish in the river to prove your point.

The point, it occurs to me now, is not the obvious one. I was going to solidify those experiments into a single pattern by the time the hatch rolled around again, but I've changed my mind. The fact is, all the patterns I tried worked at one time or another, as did an Olive Dun Quill with all the hackle scissored off, and a No-hackle Dun with the wings twisted sideways to make it look like an injured dun.

These hatches last for a long time and come off at least twice a year, so the trout see lots of both real and imitation bugs. It seems to me that what a guy needs is a good handful of patterns–all roughly the same, but each just a little bit different, too–because this isn't an operation where tab A always fits neatly into slot B. We tend to think of a hatching mayfly as having about three stages, but if you look at the bugs, you'll see that there are actually dozens of different configurations. In the course of the negotiations with a big, difficult trout, you need some options.

In other words, this is one of those hatches where you have to pay attention and stay fluid like the river itself. After all, it's a place that changes from day to day, if not from minute to minute.

Serving the Olives

Coming up with the right fly pattern for the moment is a step in the right direction, but you still have to deliver the thing convincingly. As with most mayfly imitations, the best approach is to first try the good old dead-drift: the classic, absolutely flawless, ten-yard, drag-free float through half-a-dozen conflicting currents that's such a snap for most of us to pull off Yeah, sure.

A fly angler casting on a small stream in the spring under dark gray clouds; inset image of a blue-winged olive mayfly in upper right. — Ideal Blue-winged Olive weather is cool and damp. The best approach is to fish an absolutely flawless classic dead-drift. (Main image: John Gierach; inset image: Ted Fauceglia)

If repeated dead-drifts over the same fish don't move him, try giving the fly a very slight upstream twitch. This will now and then work beautifully, but it's best to save this tactic as a last resort.

A Blue-winged Olive is a small insect, and it's unlikely that a trout will move a long way to take one. Matters are further complicated by the large number of bugs on the water during a good Olive hatch, which means a fish doesn't have to move far. So accuracy is important. The best cast is the one where you pick a specific rising trout and put the fly, as a friend of mine says, "right down his throat."

My tendency is to want to fish some sort of legitimate dry fly to an Olive hatch–that is, something that floats and has wings–but there are times when the answer is a floating nymph, or a Baetis nymph or Pheasant Tail fished a fraction of an inch below the surface.

Even though a slight variation in pattern sometimes makes a big difference, the best advice I ever got about fishing to Blue-winged Olives–or any other hatch of small mayflies for that matter–is: Don't be too eager to change flies. That is to say, first make sure you're getting a good drift and an accurate presentation. If your fly is dragging or otherwise acting unnaturally–or if it's two feet out of the feeding lane–you can throw your whole fly box out there and still not do any good.

And about those fly patterns; whatever you end up using, carry them in sizes 18 and 22, just in case that little Pseudo- or Neo-whatever is hatching. On several of the rivers I fish, the two mayflies overlap, and, although it doesn't seem logical, trout sometimes prefer to feed on the smaller insect, even when there are more of the bigger ones on the water.

But then again, if trout were logical, they'd probably be too easy to catch.

B.WO. Nymph

HOOK: Mustad 94840 or Tiemco 103, #16-#18.
THREAD: Olive 6/0 nylon.
TAIL: Dun soft-hackle fibers.
BODY: Grayish-olive dubbing.
WING CASE: Dark gray goose quill section.
LEGS: Dun soft-hackle.
NOTE: This pattern can also be tied with a shell back of dark gray goose quill and a gold or silver wire rib.