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Fly Fishing Entomology – Part 1

Monday, January 19, 2015

Entomology is the study of insects. This article focuses on the study, understanding and knowledge of aquatic insects and their influence on Montana trout when fly fishing.

Choosing a fly for the beginner fly fisherman can be a daunting task. Most fly fisherman will spend time in a local fly shop and speak to the locals getting specific information on the type of fish and the flies used to catch these fish. As a fly fisherman gets experience they become more familiar with insect matching and behaviour to better select the appropriate fly for the particular section of river, time of year and yes even the time of day. Seeing success on the river will ultimately depend on your knowledge and appropriate matching of the insect hatch. Insect hatches can last from minutes, to hours to days. The more a fly fisherman understands the hatch the better their chances of catching the type of fish their looking to catch.

Let's get aquainted to the process first. All insects that live in trout streams and rivers will have been identified and given a common and scientific name. Have a look at the two images below. The first is an actual photo of a Green Drake or in scientific terms "Baetis rhodani". The Green Drake is a fantastic insect. It is ever present on many Western and Eastern trout streams. It is large and a trout favorite.


Actual Insect: Green Drake



These insects are studied by individuals that look at each part of the insect and look to imitate them using natural and synthetic materials. Some materials for this fly are:

  • Rabbit fur for the body
  • Rooster capes for the hackle
  • Moose hair for the tail
  • And more...


Imitation or Fly Pattern: Green Drake - Parachute




Now that we have a starting point, let's summarize the decision process into two easy steps.

#1 Why A Fly

Without a fly, you don't catch fish. A fly is used to imitate an insect and when used properly will mean the difference between catching fish and going home empty handed.


#2 Which Fly To Choose

The fly selection is entirely based on what you're trying to catch and having a variety of flies available is critical.

Selecting the correct fly is not difficult after you've had a little practice. 
You'll want to determine:

  • Type of fish
  • Time of year
  • Water conditions
  • Current fly hatches
  • Appropriate fly to your fishing gear
  • Color of fly
  • Size of fly


Next Steps:

In the coming weeks, we'll be providing more information on Fly Fishing Entomology to assist anglers of all kinds to better understand the importance of aquatic insects and fly fishing for Montana trout.




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