Fishing The Blue-Winged Olive Hatch

We had flown in to the sprawling northern Saskatchewan lake for a rough-and-tumble boxing match with the water’s world-famous pike population. And the lean, green fighting machines didn’t let us down. There were violent strikes on spoons, plugs and gaudy streamer flies, rowdy battles with fish to 20 pounds that left our arms weary by the end of the 10-hour fishing day.

But in the evening, after a scrumptious camp dinner, with daylight still going strong, I found myself walking down to the outlet river from the lake near camp and wading in for a try at the pugnacious grayling residing there. Small lures or attractor flies usually worked for a few of the scrappy, beautiful fish.

Angler lands a handsome brown trout on a Pennsylvania limestone stream on a Blue-Winged Olive.
Angler lands a handsome brown trout on a Pennsylvania limestone stream on a Blue-Winged Olive.

But one evening I was amazed to see mayflies begin popping out in huge numbers. Straining to look closer, and then scooping up a sample, I saw that it was the famous Baetis species, the Blue Winged Olive hatch that I had fished in the past on so many trout waters in the East, Midwest and West.

Luckily, I had stashed a few dry flies in my gear for the trip that might work. Trimming down an Adams fly so it closely resembled the delicate little olives, I cast out and was quickly rewarded with a lunging grayling strike. As the flies continued to hatch, I drew repeated strikes on the improvised BWO imitation. It was one of the most memorable experiences in my angling life of fishing the “olives” as hundreds of hungry grayling rose for more than aWhen my mind drifts back to memorable hatches I’ve fished over four decades, none can compare with the tiny Blue-Winged Olive or Baetis mayflies.n hour on the northern Canada river.

There were days when the Olives emerged so heartily that trout fishing dreams became reality. And as the experience above shows, occasionally even other species get in on the act of dining on these ubiquitous mayflies when they hatch in good numbers. I’ve also caught smallmouths, fallfish, redbreasts, catfish, and bluegills during olive hatches, though trout are definitely the major species that feeds on them.

Another thing that makes fishing this hatch such an intense experience is that they often emerge heaviest during inclement weather. When the air is lead-gray and showers spit from the sky or winter snowflakes rush sideways through the air, you’ll likely find olives hatching.

These mayflies can emerge virtually any month, and I’ve fished them on Pennsylvania’s limestone streams often on frigid winter days. Spring can be even better, and summer and fall are also great times to find olives hatching.

Often they overshadow more famous hatches, such as Pale Morning Duns and Hendricksons. You can find them on neutral pH streams, but they do best in alkaline waters. Spring creeks and tailwaters below dams are prime. Areas with vegetation and shallow gravel runs are especially good.

Sizes of the various members of this genus can range from 4mm to 10mm, matched by hook sizes 14- to 24. The most common sizes are 16- to 20.

As far as time of day, mid-afternoon through evening is the best period to find olives emerging. Nymphs of this insect are slender and very active. Imitations of them can be extremely effective shortly before a hatch or even during its early stages. A Pheasant Tail pattern works especially well.

Author fishing the BWO hatch on Falling Spring Run in southern Pennsylvania.
Author fishing the BWO hatch on Falling Spring Run in southern Pennsylvania.

Once duns start popping out, switch to emerger patterns. As the hatch progresses, it’s time to turn to fully dressed dun imitations with erect wings. A traditional pattern will work, but I’ve had better luck with thorax, parachute, Comparadun, and no-hackle dressings. The bodies of these flies can range from bright olive to a dark, grayish brown. You can tie a variety of colors to match these various shades, or simply blend all three colors of fur into an amalgam that works well for all Baetis hatches. Wings should be medium- to dark gray.

Fishing with nymph and dun imitations may last several hours, but spinner falls can also provide excellent sport. Use a rusty brown-colored body with light to medium-gray clipped hackles or polypropylene wings to imitate mating insects. Look for them to return to the stream from late afternoon into early evening. At times a subsurface pattern, such as a Blue Dun wet fly, can produce fast action during these spinner falls.

For all phases of fishing the Blue-Winged Olives, I like a 3-5-weight rod, floating double taper or weight forward line and 10- to 12-foot leader tapering to a 5-7X tippet.

Whether you live near a tailwater fishery in the South, a big Western river or a spring creek in Pennsylvania, make sure you don’t overlook the BWO’s. They can provide some of the most exciting fly fishing of the season, and can appear virtually any time of year on waters big and small, from tiny creeks in the Smoky Mountains to the sprawling rivers of Saskatchewan.

Fish Sportsman’s Guide NOW for a great selection of Fly Fishing Combos!

Leave a Reply

Commenting Policy - We encourage open expression of your thoughts and ideas. But there are a few rules:

No abusive comments, threats, or personal attacks. Use clean language. No discussion of illegal activity. Racist, sexist, homophobic, and generally hateful comments are not tolerated. Keep comments on topic. Please don't spam.

While we reserve the right to remove or modify comments at our sole discretion, the Sportsman's Guide does not bear any responsibility for user comments. The views expressed within the comment section do not necessarily reflect or represent the views of The Sportsman's Guide.