Blue-winged olives causing fly-fishing revolution in Maine

Five years ago in late August, my intrepid companion, Jolie, and I stopped at Nelson's Restaurant in Windsor for a quick breakfast before heading to a central Maine river to hit a 10 a.m. mayfly hatch. The insect came off each morning through late summer and early fall, a reliable event.

The emergence produced fast fishing and continued for two to three hours, depending on weather. It lasted longer on cloudy days, but a glaring sun that morning would cut the hatch short, giving us but 2 1/4 hours to cast over rising trout, explaining our rush.

While ordering breakfast, we mentioned to the cheerful waitress that we were in a hurry and briefly explained why. Local fellows sitting near our table overheard us and struck up a conversation. I grew up in Windsor so knew most of them anyway. We talked about insects and predictability, which fascinated the men -- all non-fly rodders.

The mayfly that interested us that day belongs to the Baetis genus. Like most aquatic insects in that genus, it has smoky-blue wings, tails and legs and an olive body and goes by the descriptive name blue-winged olive or the acronym BWO. One key to identification is two tails instead of three.

Baetis mayflies are swimmers as opposed to crawlers, clingers and burrowers, so they are more readily available to foraging trout than critters hiding under rocks or burrowed in silt. More and more Maine fly rodders are targeting this genus because these swimmers provide sizzling fly-fishing action.

The shade of blue-gray and olive varies greatly with the species as does the size. That day, a fly with a light-olive body and pale, smoky-blue appendages on a size 24 hook matched the mayfly -- about the size of a mosquito. Baetis mayflies run from size 14 to 28, the latter really tiny.

When Jolie and I were paying the bill, we heard the men talking about us, and they were clearly impressed that anglers could time a fishing trip on a dependable hatch. However, I've been noticing that particular mayfly for a goodly part of my adult life, giving me ample time to figure out schedules. In short, my knowledge required little intellect beyond simple observation.

Within my lifetime, Maine has undergone a major fly-fishing revolution that has sprung off blue-winged-olive hatches, most of them in the Baetis genus. It started slowly in my youth but has picked up momentum in recent years. Folks plan vacations and daily trips around these BWO events.

Insects in the Baetis genus emerge predictably from May through November, and the emergences of several species increase now as we head into the fall-fishing season. In autumn, I may fish weeks at a time, using nothing but BWO imitations.

In fall, BWOs often emerge at10 a.m. or 2 p.m., depending on the species, and these times create bankers' hours for fly rodders. In October and November, frigid waters become the warmest in afternoon, so 2 p.m. hatches rule. The 10 a.m. hatch dominates in spring-fed streams or tail-waters in early fall, but in rivers where water temperatures soar, BWOs come off shortly after sunrise when rivers and streams flow coldest.

Trout and salmon often key on size and body color, so fly rodders must have a good array of BWOs in different sizes and olive shades. Sometimes, though, picky, hard-fished trout get finicky and want the exact blue-gray on the wings, tails and legs as well as the right olive and size.

A grand book for studying Baetis and similar swimming genera under the colloquial name blue-winged olive is Mayflies with the subtitle An Angler's Study of Trout Water Ephemeroptera, written by Malcolm Knopp and Robert Cormier. Pages 43 through 67 give beginners a solid foundation BWOs.

The beauty of BWOs, though, is this: You need not know the Latin names of the insects. A goodly array of BWO dry flies and emergers for matching an imitation to a natural in 1) size, 2) color scheme and 3) silhouette will keep the good times rolling. In short, fly rodders capture the insect enticing the feeding fish and match a dry fly or emerger in those three categories. Compara-Dun and thorax-style BWOs are perfect for matching the hatch with dry flies.

Pheasant Tail nymphs in sizes 14 through 24 also fool trout during and before this hatch because the pattern imitates Baetis mayflies in the larvae form. The technique for fishing this generic nymph is as old as fly fishing.

Fly fishers cast the Pheasant Tail quartering across and downstream, let the submerged fly swing on a tight line and retrieve it by rolling the line over the fingers, which inches the fly along.

This simulates the swimming nymph and can keep a rod bent all day long. A weighted Pheasant Tail or split shot on the leader improves the odds of catching trout when nymphing over Baetis.

The Baetis genus has started a fly-fishing revolution in Maine during the early 21st century because these mayflies have attracted huge attention. The sale of BWO dry flies and emergers has risen each year to meet the demand, and Pheasant Tail nymphs have become a perennial favorite.

Maine trout waters are full of Baetis mayflies, and they hatch heavily for seven months each year, making the genus a favorite. For the slender-wand crowd, this 7-month event has really helped make Maine life the way it should be.

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