Entomology Part 2 – Choosing a Fly

Photo: Eric Neufeld

As I mentioned before, presentation and fishing technique plays a more significant role in catching fish.  In most instances if you have confidence in your fly, you’ve made a cast in the correct location with a good drift; you’ll be successful.  Regardless if your fly is pink and bedazzled or all natural materials, ANGLER CONFIDENCE plays a huge role!  Fishing Techniques Blog to come.

Review of Entomology – Part 1.

  • Dry Fly = Adult Stage of Bug
  • Subsurface Flies = Immature Stage of Bug
  • Streamer = Mimics Bait Fish and Other Large Aquatic Prey.

There’s still a few other basics before we dive into the different bug species and their life cycles.

Photo: Eric Neufeld

You’ve strung up your rod, chose the correct leader and tippet size (see the tippet equation below), where in the world do you go from here?  You look at your box of flies and have no idea which one to start with. Do you tie a fly on before you hit the water?


The first plan of action should always be doing research on the river you want to fish.  Check out the local fly shops “Fishing Report” or better yet go into the shop and talk to the staff directly and purchase some of the recommended flies.  The relationships you develop with the shop could be priceless.  Find out what specific bugs are hatching during the time of year.  There are several websites that have Hatch Charts for rivers and lakes around the world.  All you have to do is search Hatch Chart.

Reach out to local clubs, local online groups (UWOTF Closed Facebook Group) and the local fly shops list of suggested flies.  If you have no idea what a Purple Haze or Masked Marauder is then Google it, click on images and look at your fly box to see if you have anything that might mimic it.

Photo: Denine Austin

You’re going to be much more successful if you do a little research!

As a nurse I start the day off by walking into my patient’s room and assess my patient’s status and surroundings.  Is the patient awake, alert and oriented?  Do I have all the equipment I need in the room if something were to happen?  How does the patient look, dry and pink?  This is the same with fly fishing.  Look around, assess the river, are there any bugs flying around, are the fish feeding on these bugs, what are the fish feeding behaviors?

Putting a fly on before you hit the water is personal preference.  I, personally, tie a fly on while setting up my rod at the car or on the boat.  Other anglers wait to tie on a fly until they are on the water.  I tend to tie on an attractor fly to start unless I have other intel on what the fish are eating.


It’s best to error on the side of smaller.  What do you see around? Pick up rocks in the river, what size nymphs are crawling around? Were there any grasshoppers jumping around as you made your way to the water?  Any ants or beetles crawling around the vegetation or shore?

Choose a similar size (or smaller) fly to what you’ve assessed.

Do you know what size tippet you should be using with a specific fly size?  Does your fly not turn over correctly when casting?  Or is your fly rigid on the water and doesn’t look natural?  Matching the correct tippet to your fly size can help solve these problems.  As a general rule you take your hook size and divide it by 3.  Remember as the hook size goes up the hook itself is smaller.

For example a size #2 fly is significantly larger than a #18.

I personally do not own 7x tippet and will occasionally use 6x. The most common tippet spools that I carry are 3x – 5x.  Therefore you’ll notice in the graph above that I don’t always follow the general rule.  This concept will, however,help you get a better cast and fly presentation.


You’ve assessed the bug size, now what profile (fly) to choose?  You’ve probably noticed by now that there are thousands of different designed flies with names that have nothing to do with the actual bug.  Here are a few hints for deciding what type fly to use.

Hint #1 – Feeding Behavior

Did you know that mayflies have a vulnerable state between their emerger to adult (Dun) stage?  The Mayfly wings are not fully dried when they reach the water surface.  The opportunistic trout take advantage of this state and feed more leisurely. You’ll see water rings, noses coming up and fish sipping on bugs in the film.  I refer to this as “Symphony Feeding Behavior”.  The fish are more relaxed, taking their time to feed on the adult mayfly. Similar to drinking wine, eating cheese and listening to the symphony.

What’s the opposite of the relaxed symphony? ROCK-N-ROLL! Unlike mayflies, when caddis pupate to an adult, they are ready to go.  There is not a vulnerable state and their flying pattern is erratic.  They immediately spread their wings and fly.  I refer to this as “Rock-N-Roll Feeding Behavior”.  You’ll see a more aggressive take and feed.  Larger splash’s and fish coming out of the water to eat the bugs.  Think ACDC or Led Zeppelin.

Hint #2 – Observation

  • Mayfly
    • Adult have a Sailboat Wing
    • Controlled Flying Behavior
    • Varied Sizes #10-#24
    • Nymphs – Three Tails
    • Hatch in Water Temps Beginning Middle 40s

  • Caddis 
    • Tent Like Wings
    • Erratic Flying Behavior
    • Varied Sizes #12-20
    • Larvae – Cocoon Like Structures
    • Hatch in Water Temps Beginning Middle 50s

  • Midge 
    • Looks like a Mosquito but doesn’t Bite
    • Small and Hardy – #18-#26
    • Hatch Year Round in a Variety of Water Temperatures Above 32 Degrees

  • Stoneflies 
    • Erratic Flying Behavior.
    • On Average are Larger than other Aquatic Insects
    • Extreme Variance in Size – #2 – #20
    • Crawl to Shore and Break Away from Exoskeleton
    • Nymphs – Two Tails and Two Antennas
    • Hatch in Water Temps Beginning Middle 50s

Hint #3 – No Top Water Feeding

This might be the most important hint.  Again, fish feed about 80% under water.  If you don’t observe any fish feeding on top, then you might consider adding a nymph (wet fly).  Second choice would be to fish an attractor dry fly using the same drifts and fishing techniques as you would fishing an imitator.

Photo: Tiffany Hansen


Does color matter? ABSOLUTELY?  Do fish see color? I’m not sure.  I can tell you from my personal experience that many times matching the color of the hatch has helped lead to a successful evening of fishing. For example, during a PMD hatch I’ve caught more fish with a a size #16 yellow parachute than a size #16 gray parachute Adams.

My bachelors degree is in nursing and not fish biology.  There are several blog posts and books in reference to this debated subject.  For further reference, please do a little research.  Here’s a good read from Midcurrent.com.


  1. Assess your surroundings.
  2. Observe insect size.
  3. Choose a fly that mimics the hatching species with an imitator fly.  If there is no hatch, consider fishing subsurface or using an attractor dry fly.
  4. Fish a fly that is similar color to the profile/size insect you’ve observed.  If matching the color does not work, try thinking outside the box with attractor colors and different fly patterns.


We’ll start diving into the specific insects and their stages of lives next.  TO BE CONTINUED…..












Comments (1)

Great read! Thank you. I’m headed to Idaho in September and this sure will come in handy.
Fish on!!!!

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