The Blue Winged Olive hatch is often the first sign that spring fly fishing is under way. This mayfly hatch provides opportunity from the stream bed up to the river's surface for trout fishing. Trout will actively feed on nymphs, then emergers, and finally adults over the course of the day. Fly fishing with a nymph rig in the morning, drifting emergers mid-day, and throwing dry flies at rising trout in the afternoon is common in the spring and fall.
Blue Winged Olives often hatch during foul weather. Days where most people would rather be inside, may provide glorious memories for the savvy angler. Since trout will key on each phase of this hatch it’s important stock your fly box with flies that represent all three life stages—nymph, emerger, and adult!
In short, mayflies in the Baetidae family are called Blue Winged Olives . There are over 150 described species in Baetis (genus) . They are distributed worldwide, with a huge variety in North America and Europe.
Blue Winged Olives can be imitated with a variety of nymphs, emergers, cripples, and dry flies. They range in size from a #16 to 22. The most popular patterns are often small and simple.
Nymphs: Most Blue Winged Olive hatches will produce a large number of nymphs. Nymph patterns should match the size and shape of the insect on your river as closely as possible and be fished with a dead drift.
Emergers: As nymphs mature, they begin to rise to the surface where they pop their wings and transform into adults. Emerger patterns represent nymphs as they are rising to the surface.
Cripples: Cripple patterns imitate emergers that are struggling to break through the surface film. Trapped between larva and adult they dead drift with the river's current providing an easy meal for trout. Often cripples will produce better than duns.
Duns: Dun patterns imitate the adults as they hatch from their nymphal shucks. Duns are often the most visible stage of the hatch and trout will key in on them. Prolific trout streams like the Green River in Utah can produce blanket hatches of BWO which is a sight to behold for any fly fisher as trout heads pop through thick mattes of bugs to gorge on tiny insects.
Trout focus on the best bang-for-the-buck. They station in the water column based on where food is most prevalent. Their feeding behavior will tell you which stage of the blue winged olive life cycle they're focused on. Early in the hatch, feeding trout stay low in the water column eating BWO nymphs. As emergers begin moving towards the water’s surface trout will transition to a mid-column station. Once there are ample numbers of Blue Winged Olive duns and cripples, trout will focus their attention skyward and begin taking flies off the top.
As with most species, it is important to match the size and color of the Blue Winged Olive flies that you use to the insect on the water. Get the size, color and life stage right and your fly fishing success will quickly increase.
You should select nymphs in size #16-20 with olive bodies depending on the size of the naturals in your river. (Click here to see how to figure out the bugs that trout are eating). Flies should be tied sparsely.
Pheasant Tail- Olive or natural: The PT nymph is a great general mayfly nymph. It can be used to match several different species of mayflies, the BWO included. Tied with the tail feathers of a pheasant and peacock herl for the thorax it is one of the most successful flies ever created. I carry several variations of the PT Nymph in bead head and standard in my fly box whenever I am fly fishing.
Like the PT, the Hare’s Ear is one of the most effective all-purpose mayfly nymph patterns available. Tied with natural hare’s ear dubbing, feeding trout find it hard to resist. Remember to tie it sparsely.
Designed by Mike Mercer, the Micro-May is a fantastic representation of the BWO. It is a great pattern to use when the bugs are small and the trout are picky. Tied on a size 20 or 22 scud hook, this fly is perfect for those days when the bugs are small and nothing else seems to work.
Emergers can be tricky to match because they are in the process of changing from a nymph to an adult. These flies should be tied in sizes #16-22.
Several flies fit into this category. CDC is short Cul de Canard, French for Butt of the Duck. Adding CDC feathers to any pattern is a bonus in my opinion. CDC emergers are one of the most effective patterns for imitating the BWO. The distinguishing factor of the CDC emerger is the post or wing of CDC extending out between the abdomen and thorax which is designed to imitate the newly minted wings and body breaking free from the nymph husk. The RS2 is a good example.
It's called a dun but really it resembles an emerger or a cripple. Tied with a dun-colored parachute post and hackle and olive body, it rides in the surface film but is still easy to see. This is a great pattern to use when the trout are rising but you can’t tell exactly which stage they are eating.
Creative fly tiers have designed patterns that represent insects caught between their emerger and adult stage that give the impression of helplessness that trout just can't refuse. Oftentimes during a BWO hatch, I use cripples until the trout quit eating them. Which is generally when the hatch is long over.
The Quigley Cripple was developed for the Fall River in Northern California by Bob Quigley almost 50 years ago. The Fall River is flat and clear. Feeding trout have plenty of time to study your fly. It is a fantastic fly that bridges the gap between adult and emerger. The abdomen is tied with pheasant tail fibers and looks like a nymph and the thorax is dubbing with deer hair wings, finished with a dun hackle. Tied in size #16-20 this fly will become a go-to fly for you for several species of mayflies.
An offshoot of the Quigley Cripple, the Last Chance Cripple was developed by Rene Harrop. The design is similar but the materials have been changed. The tail is wood duck or grizzly hackle. The abdomen is goose or turkey biot dyed to color. The wing and thorax are CDC (remember what I said about CDC?) And the hackle can be dun or brown grizzly. Tied in size #18-22, this fly is perfect for those days when trout are super finicky.
As the hatch hits full swing, trout turn their attention to the surface. Adult BWO patterns should be tied in sizes #16-20 and should match the color of the local species as closely as possible. Freshly hatched adults ride the surface of the river until their wings are dry enough to take flight. At this time they are easy prey and trout know it.
The Comparadun may be the ultimate mayfly imitation. Depending on how you treat it can be fished as a cripple, a dun, or if you clip the top deer hair, as a spinner. It is an easy fly to tie and can be fished with confidence in a variety of water conditions.
Developed by Doug Swisher and tied like a traditional parachute pattern in sizes #16-20, the Clumpa uses a rubber leg for a parachute post. Before finishing the fly, the post is pulled forward and tied behind the eye, changing the profile of the hackle. It is a deadly fly... but if you have a problem seeing parachute flies on the surface, this one will be impossible. Maybe go with the next bug.
A synthetic post that is easy to see and a tail that helps this fly float like a cork are complimented by a dun hackle that is trimmed so that it rides low. This is a great bug for anglers with experienced eyes... Even in size #16-20.
I start by fishing a nymph rig early in the morning before heads start popping then switch to emergers as the hatch begins. As the hatch intensifies, I switch to a cripple and fish it until the hatch subsides or the fish tell me they only want duns.
The best way to fish a Blue Winged Olive hatch is to work the cycle with the fish. Be prepared with flies that represent all three life stages of the Blue Winged Olive. By doing this, you will be ready for whatever the hatch and the fish throw at you.
