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Tips for Fishing Spring Blue Winged Olives

Warmer spring temperatures bring a welcome change around here. But if you’ve been in Colorado long, you know it won’t be a smooth ride from here to summer. There will be more snow, cold rain and sleet. But keep one thing in mind: those nasty spring days create the perfect conditions for hatches of Blue Winged Olives.

These small mayflies thrive on those cool, overcast days. From about the end of March through late May, don’t let a drizzly day keep you off the water. It could be the perfect day to experience a Blue Winged Olive hatch.


What Is A Blue Winged Olive?

When we use the common name, Blue Winged Olive (BWO) or Baetis, we are actually referring to multitudes of mayfly species that belong to the Baetidae family. For anglers, it isn’t all that important to be able to identify every genus and individual species in the Baetidae family. If you enjoy taking deeper dives into these types of topics, the information is available. However, being able to differentiate between a Baetis flavistriga nymph vs. a Baetis bicaudatus nymph is not going to be all that helpful...


Mayfly Clinger Nymphs vs. Mayfly Crawlers - A Crash Course

If you were to break mayfly nymphs down into 4 categories, they would be clingers, crawlers, swimmers and burrowers. The first two categories are the ones on which we want to focus.

Clinger nymphs and crawler nymphs are extremely similar and differentiating the two is not all that important for the everyday angler’s purposes. If you’re looking for a more in-depth look at the differences/similarities among the categories of mayfly nymphs, check out Phil Rowley’s analysis on his website FlyCraftAngling.com.

For sake of application, clingers and crawlers can be imitated with the same fly patterns. But before moving on, here are a couple of lines on why these two groups received their respective monikers:

Members of the “clinger” nymph group earn their name by their tendency to cling to aquatic structures and other submerged objects to seek refuge from their moving water habitats.

Members of the “crawler” nymph group do just that - they are characterized by their ability to stay down and crawl along the river bottom.

Mayfly clinger and crawler nymphs (with very few exceptions) feature 3 tails, which makes it easier to differentiate them from other aquatic insects like damselflies. Clingers will lose one of their tails as they mature, whereas the crawlers maintain all 3. Their bodies are wide and flat, with large eyes on a small, flat head. The eyes of clinger mayfly nymphs are located on the top of the head, while the eyes of crawlers are located on the sides. Clinger nymphs are generally larger than crawlers.

Neither clingers or crawlers are great swimmers. Both groups are vulnerable to trout when they are dislodged from their homes by a catastrophic event, like a sudden, drastic increase in streamflow. The nymphs also become vulnerable during dispersal drifts, in which the bugs release from their hiding places and migrate downstream en masse in search of a new habitat.

Because of all the similarities, many flies designed to imitate mayfly nymphs are generic, “close enough” patterns. And, if you ask us, one of the best clinger/crawler mayfly patterns on the market today has to be the Micro Matcher.


Meet the Micro Matcher

Invented by Colorado native and Umpqua Signature Tyer Scott “Walter” Newman, the Micro Matcher was designed with purpose - but also out of frustration. We could tell the story, but we can’t do it justice like Walter can. Here’s an excerpt he wrote on his fly for the Umpqua website:

“The inspiration for the Micro Matcher came after a tough day fishing on one of Colorado’s tailwaters. I had noticed a lot of baetis in the water and couldn’t find the right size and profile I was looking for in my fly box. That’s when I decided I needed to create a bug for these scenarios.

The Micro Matcher was born as a three-tailed mayfly/baetis nymph with three sets of rubber legs for some added motion and appeal, combined with a great baetis profile. This fly has saved many days for my friends and I since its creation. I hope that it will do the same for anglers everywhere.”


MATERIALS LIST - Micro Matcher

Hook: Tiemco 101 Sizes 18-22

Thread: Ultra Thread 70 Denier

Tail: Mayfly Tails 

Rib: Ultra Wire - Silver - XS

Wing Case: Thin Skin

Thorax: Superfine Dub

Legs: Senyo's Shaggy Dub


Fishing a BWO Hatch

Nymphs become active in the morning and again in the evenings. So even when there’s no apparent hatch, baetis patterns like the Micro Matcher can be effective. As the clingers and crawlers move down the streambed, fishing these nymphs with a tight line or even swinging them can be a productive tactic.

On those cool, overcast days look for hatches of Blue Winged Olives from late morning through the afternoon. We all love a good dry fly eat. But pay attention to where the trout are keying in. During these periods it’s common for fish to be snacking on emergers before they hit the surface. When that’s the case, look to patterns like the popular Barr’s Emerger or Peterson’s Batwing Emerger. Try fishing it below a dry fly, just below the surface - or as a part of a nymph rig.

This can also be a great time to swing a soft hackle through the current. When emergers are actively on the move during a hatch, tie on a Pheasant Tail Soft Hackle or a Palm’s Biot Emerger. Make quartering downstream casts and swing the fly through the current just upstream from your target.

A BWO hatch can bring periods of great dry fly fishing, But seeing these little dry fly patterns on the water is a challenge. The flat light and cloudy glare can make it extremely difficult to keep track of the white post on mayfly patterns like the Parachute Adams or Parachute BWO. When that’s the case, try fishing a dry fly pattern with a dark wing or parachute post. You may find that it’s easier to see in tough lighting conditions.


Contact Us With Questions

Have questions or need help getting ready for your next day of spring fishing? Visit us at the fly shop in Littleton. Or give us a call at 303-794-1104. We’d be happy to help with fly patterns, rigging or anything else you need. All online and phone orders can opt for either free shipping or same-day curbside pick up.