Entomology for Fly Fishers

THE IRIDEUS - SEPTEMBER 2019

Entomology for Fly Fishers

With Mark Likos

Entomology is the study of insects. For those of you that missed the August club meeting this article summarizes my talk.

Success in fly fishing is all about capitalizing on probabilities. One of the ways to maximize your probability of success is through an understanding of foundational-entomology. You don’t need to be an expert in aquatic insects to step up to high-performance fly fishing. With a little knowledge of entomology and the application of a few steps, you can boost your productivity substantially.

The vast majority of a stream trout’s diet come from 3 insect groups. The majority of those will be subsurface. IF WE CAN IDENTIFY what the trout are currently eating, we have a huge advantage over those that don’t. We can present what the trout are currently looking for rather than just guessing at what imitative fly to use.

Trout, will eat a multitude of aquatic insects in addition to a few terrestrials, but the vast majority are eating one or more of The Big 3. Namely, some stage of Mayflies, Stoneflies or Caddis Flies. These insects make up the majority of the trout’s diet. They all start life as a subsurface aquatic insects and transition into air breathing terrestrial insects as an adults.

A female subimago of March Brown (Rhithrogena germanica) mayfly resting on a Rough Horsetail (Equisetum hyemale) stem. Image reuse courtesy of Richard Bartz under Creative Commons License.

Our outing success will depend on our ability to identify which of the Big 3 is currently in the waters we plan to fish. Local fishing reports and hatch charts indicate what is normal for the time of year you are fishing. Local fly shops & guide services are excellent sources of current information on what the fish are taking, effective fly patterns and water conditions. Once on the water you can use a seine to collect insect samples. The internet has several useful videos on using overthe-net and two handed seines. Some anglers even use a stomach pump to determine what the first fish they catch was eating.

Match your fly (size, shape & color) to what you find in the water and your success rate will soar!

If you are interested in the August presentation where I cover the subject in much more detail, contact me at mlikos@comcast. net . I’m close to completing an audio file of the presentation to send to interested club members.