An Entomologist in Your Pocket | The Fly Predictor

This tool will identify the insects most likely to occur in the water you're fishing, and make fly recommendations for each phase of insect life.

by Chris NApril 06, 2023 in Fly Fishing Tips and Techniques

We met Donny and Chris – co-founders of Trout Edge and Fishing Culture – months ago. Donny is a long-time customer.

Donny has a PhD in Ecology. He is a walking bug encyclopedia. When we asked him to provide a few thoughts on the Baetis hatch last year, here’s what he sent back to us:

“BWOs are important because they:

  • Are often more abundant and available to trout than other aquatic insects,
  • Produce reliable and sustained hatches (typically beginning in early spring and continuing into fall), and
  • Regularly produce hatches during the daytime that are prolific enough to cause trout to feed selectively and on certain stages (emerger, dun, spinner).

For all of these reasons, "having a good selection of BWO nymph, emerger, and dry fly patterns, in a variety of sizes and shades (gray, brown, or olive bodies), is important to consistent success on the water."

Clear, succinct, easy to understand, and applicable. So, when Donny and Chris approached us about being associated in a small way with a special project they were working on, we knew that it would be awesome. After years in the making, Donny and Chris are launching the Fly Predictor. The Fly Predictor is an app that identifies the insects most likely to occur in streams, rivers, and creeks at a given set of geo coordinates. Said, another way, drag your finger on a map to a specific body of water, and the app will tell you the bugs most likely to occur in that water. It’s like having a fishing buddy that is an entomologist, but without them bugging you with bad insect jokes! The app will also show you pictures of the naturals during all phases (e.g., nymph, emerger, adult), link to suggested fly patterns for each phase of emergence, and give a tip or two about fishing these bugs.

The app is subscription based. Along with a monthly fee, members get 5% Off all flies at DiscountFlies. Check out the Fly Predictor at: .

Here’s a sneak peek! The App currently covers eight states:

Fly Predictor Covers Eight States
Fly Predictor Currently Covers Eight States

To explore an area, simply drag you fingers on the map and then press “Search”:

Easy to Search
Easy to Search

You can read more about the specifics in the FAQ below, but the App uses AI and machine learning to analyze thousands of data points:

Powered by AI and Machine Learning

When complete, you get a full list of the bugs most likely to be found at the geo location:

The App uses AI and machine learning
A full list of the bugs most likely to be found at the geo location

For each of the insects listed, you can learn more about the bugs. Perhaps more important, Donny and his team focus on translating that bug knowledge into FISHING knowledge:

Learn more about each of the bugs
See pictures of the naturals if you want to compare to what you're finding

You can even see an entomologist’s fly recommendations and buy the bugs you need:

Use an entomologist’s fly recommendations to build an entire fly box of bugs that will cover all the most likely insects to occur in all their stages (nymphs, emergers, and dries) where you're fishing

Some FAQs about the Fly Predictor:

Does the fly list change at a location based on time of year?

No, the fly list does not change based on the time of the year you use the fly predictor. However, the life stage of the fly may change depending on the time of year you are fishing. For example, Drunella grandis will be a nymph during the fall, winter, and most of the spring, but it will be a flying adult during parts of late spring and early summer. Additionally, there are a few weeks in early summer where Drunella grandis will be in its egg stage prior to hatching into a nymph. On the fly information page, we provide some information about when to be on the lookout for the different life stages. For example, if you are fishing in the spring, be sure to have some large nymph patterns and some dry fly patterns just in case!

Does the fly predictor work on ponds and lakes?

Not currently. The models used to predict what insects will occur were only trained with data from streams and rivers, so these are the only types of water that the fly predictor can make predictions for.

Does the fly predictor work on all streams and rivers?

Almost, but there are a few exceptions. The fly predictions made on tailwaters below dams, and other streams and rivers that have been heavily altered in some unnatural way, may be less accurate.

Why does the website disconnect from the server?

One reason is due to high website traffic in which case the server may not be able to handle all of the requests. Another reason is due to inactivity (after 5 minutes). Try refreshing your browser and searching again.

What does the % Match column mean?

The % Match column is interpreted similar to the % Match provided by platforms such as Netflix. For example, Netflix uses machine learning models to provide a % Match for movies that it predicts you will like based on your movie viewing history. The fly predictor website uses machine learning models to provide a % Match for flies that it predicts will occur at your entered location based on characteristics of locations that the flies were found in the past. For example, a % Match of 90, indicates that it is very likely (90% likely) that the insect is found at the entered location.

What is machine learning?

A machine learning model is a type of predictive model that uses large datasets to learn patterns and then make predictions. For example, the fly predictor software uses large datasets of aquatic insects and environmental characteristics (such as temperature, precipitation, water chemistry, habitat, geography etc.) collected at locations across the state to learn where each insect is likely to occur given its environment. When the user enters a lat/lon, the model queries a database with associated environmental characteristics of the entered location and predicts the probability or likelihood that each insect will be found at that location based on the specific environmental characteristics of the location.

Is the fly predictor a substitute for a local fly shop?

Absolutely not! The fly predictor is meant to be a first source of information about flies that are likely to occur in the stream or river where you will be fishing. The fly predictor is especially useful when fishing trout streams that are less well known and that don't have fly shops located nearby. However, there is no substitute for the on the ground experience and knowledge of a local fly shop and fishing guides.

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