Choosing the Right Fly

Posted July 2016 (Updated April 2020)

How do you decide what fly to use? When I was first starting to fly fish, choosing which fly to tie on always presented a quandary. I would fill my fly boxes to overflowing with fly patterns of every shape, size, and color. I usually would tie on the last fly I used that worked. If unsuccessful, I would rifle through and empty my fly box randomly trying various patterns until I found one that happened to work. If my fishing buddies were landing fish, I’d ask what they were using and switch to that fly. Sound familiar?

Knowing when and why to use a specific pattern requires understanding how conditions drive trout behavior. This insight will peel back the layers of mystery in choosing the right fly and is applicable to any lake whether you are using dry flies, pupa patterns, or streamers.

Match the hatch only when trout are selectively feeding on the adult stage of the aquatic insect
Fly fishing anglers have long followed the tradition of matching the hatch. In my experience, I have found that matching the hatch is productive when trout are selectively feeding on the adult stage of insects. During these times, the fly needs to closely mimic the size, shape, and color of the adults.

I have found that size is the most critical factor. If the size does not approximate the natural, it likely will be refused. Secondly, the shape (profile) must match the natural insect, and lastly, color. In my experience, color is the least critical because when trout look up toward a sunny sky, the fly’s silhouette is backlit and its color becomes indistinguishable.

When trout do selectively feed on the adult stage it is only for a short period of time during which other available food sources are often ignored. I experienced this just before an epic mayfly hatch while fishing a lake in Wyoming. Using my white AP Nymph pattern, I landed several 18-inch trout. The bite stopped as soon as the mayfly hatch started. I then switched to a dry fly pattern and landed three more trout during their brief feeding on adult mayflies.

The feeding frenzy was cut short when windy conditions forced the adult insects off the water. Immediately the trout stopped feeding on the dry fly but were lured back again when presented with my AP Nymph.

I have not found it necessary to match the hatch when trout are feeding below the surface. My experience mirrors what I have read: Trout feed 80% of time on the pupa stage of the insect, 10% on the adult stage and the other 10% on other food sources.

Jason Randall states in his book, Trout Sense, a Fly Fishers Guide to What Trout See, Hear, and Smell (Stackpole/Headwater, 2014), “It can’t be overstated the most important search image for trout , especially when the prey species is an insect, is to match the correct stage of the life cycle.”

Fly selection should therefore primarily favor pupa patterns. For example, standard patterns popular in most fly boxes include the prince nymph, pheasant tail, hare’s ear, and zug bug. These patterns all suggest various aquatic insects in the pupa stage of development. Whether the fish take patterns as a chironomid, caddis, or mayfly nymph, who knows?

It is not the specific species of insect the fly represents. What is important is that all these patterns represent the pupa stage of aquatic insects. When the fly is viewed as food, it will trigger the trout’s opportunistic feeding response regardless of whether the fly’s appearance mirrors a specific species of aquatic insect.

Pattern selection is based on three factors: conditions, time of year, and time of day

Conditions

Factors like barometric changes, rain, wind, sun, and rapid temperature shifts impact water conditions and subsequently trout feeding behavior. Active feeding behavior can precede an incoming front, and in many cases, the bite will briefly accelerate.

Keeping an eye on barometric pressure trends is important as they can indicate changing weather conditions. A changing barometric pressure may indicate that a storm is coming. The bite tends to fall off when the barometer is fluctuating. The bite will return to normal after the barometer has stabilized. In my experience, a low barometer does not necessarily translate into doom and gloom. Rather, the bite falls off during the time that the barometer is in flux.

Windy and Stormy Conditions

Clouds, wind, precipitation, and abrupt temperature changes may drive trout to seek cover in deeper water and/or underwater structure. For example, while fishing in Nevada, an incoming storm front arrived bringing strong winds.

Trout moved from the top two feet down to a 3-5 foot depth. I switched from a small nymph pattern to my weighted Predator Bugger. Once the fly dropped to 3-5 feet I continued to get hit.

Incoming Storm Front

When windstorms are severe and long in duration, I find trout will stay sheltered and uninterested in eating until conditions change. It may take several days before trout will go back on the bite. Under such conditions, spend some time at your fly-tying bench or attack your honey-do list until conditions improve.

Light Surface Ripple

Surface ripple provides trout protective cover. Trout feel safer to feed and will feed higher in the water column. When aquatic insects are active, select pupa patterns like my Grizzly Bug. Trout will be feeding in the top three feet or along shallow shorelines depending upon the time of day.

Clear water conditions

Use your favorite bright color flies. When sun is on the water and the aquatic insects are active, tie on a pupa pattern and fish the top few feet. If you see shucks in the water, you know that there has been a recent hatch and it’s a good time to use flies like my UV Midge Pupa.

 

 

Time of Year

Proper fly selection also dictated by time of year. This is because the time of year determines what food is available. In early spring or late fall, patterns like my Predator Bugger and Predator Leech are productive due to the absence of aquatic insects. Midge patterns like my UV Midge are productive all year since chironomids are a staple year-round food source for trout.

In summer, when the water temperature increases and aquatic insects begin to emerge, use impressionistic patterns mimicking aquatic insects like my UV Emerger.

During the fall, I decrease the size of the fly because insects during that this time of year are smaller. Larger flies that work well in the spring may now scare away fish in low, clear water.
During the winter months, due to the colder water and presence of fewer aquatic insects, my UV Midge and Predator Bugger have been effective in enticing reticent trout into a reactive bite.

Time of Day

Early morning and late in the day, during low light conditions, use streamer or minnow patterns. My Predator Bugger, Predator Minnow, or Predator Leech patterns are productive along shallow shoreline edges at these times. Large trout venture out in low light seeking tasty morsels of protein because they feel safer under these conditions.

Hatches start mid-morning. When I start seeing rings, I change my fly to an aquatic pupa pattern.

Tips when the conditions cause the bite to change:

Keep Moving – There are no fish where you are fishing. Not getting hit likely indicates the absence of feeding trout. The solution is, move to other areas where trout may be feeding.

Cast in a different area – There may be fish, but the cast may have spooked the trout. Avoid recasting in the same area because fish will move away due to the disturbance in the water.

Probe Different Depths – You may be fishing at the wrong depth. Your fly may be moving at a depth of 6 feet, but the fish typically are feeding two feet from the surface. Try probing different depths.

Note: If there are any questions that you would like me to answer, please send them to me using the contact form. I would be delighted to hear from you.

 

 

 

 

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