Welcome to Not Quite Entomology

Welcome to Not Quite Entomology! This is a different approach to matching the hatch, or learning which insect the fish are really eating. The flies and methods to make it all work will be here as well. We hope this series will inspire you to go out, look on top of and under rocks, check the stream-side vegetation, really investigate your favorite water and learn which are your local trout's favorite foods!

Blue-Winged Olives

Old Rupe!
By Old Rupe

Ephemerella attenuata
The green curse. Buy your new glasses before you fish this hatch. It will run from 16's to 24's in a heartbeat, but it's the first mayfly hatch on the water for most of us. Why the broad range in size? Well, in Wisconsin alone 17 different species are listed. It's like trying to classify Americans under one ethnic group. The size and color are about all they have in common, except the nymphs are all swimmers. Most species are multi-brooded and like a bad guest arrive early and stay late. Ephemeralla attenuata is the actual insect involved, but regionally another dozen of mayflies are called Blue-Winged Olives (BWO) or just "baetis" which is another species.

In the west it's mid-March until the last of November while in the east it runs from early March to mid-October. These flies seem to be somewhat temperature dependent so a warm spring will bring them on earlier. Old timers in the mid-west like me remember when the hatch was timed by when a particular flower appeared. Easter Lilies if I remember right, not the first of the hatch but more or less at its peak. Early April here.

This fly is not only multi-species, but also is multi-brooded. Depending upon the fertility of the stream there can be 3 - 4 broods a year. As the season progresses the flies diminish in size from a 16 or 18, to a 24 or smaller.

These flies seem to emerge when the water temperature rises above 40 degrees F. in the spring and depending on temperature it can happen from 10 a.m. to 3 p.m.. The hatches stay on the water for about an hour or so except in misty rainy weather where I've seen hatches last six hours or better. Later in the year I've seen them hatch at 6 p.m. and I've read that under hot dry summer conditions some even hatch at night.

As with any multi-species group there will be great differences in when and where they will hatch. Different animals live in different environments and consequently behave differently. A lot of different things here.

Warm days seem to compress the hatch while cool misty days seem to prolong it.

One would expect a multi-species group to hatch at different places and it does. Some in the fast riffles and others in the slow current adjacent to the weed beds. Here the best action is just off the weed beds about a foot or so.

Baetis nymph How do we fish this hatch? Well no one does it the same. Early on I see a weighted nymph close to the grass beds swinging out as a winner, while later I try an un-weighted nymph real close to the weeds. I try to fish it dead drift. As the hatch progresses I use a soft hackle or a floating nymph dead drift just off the weeds. When I see the rises I go to my 16 - 20 parachute with 5 - 6X long leaders and I'm in heaven. My impression is that during this hatch most trout station themselves in the stream and don't move very far to intercept their prey. Timing to a rise can be very important. Even during the pre-hatch period trout don't seem to move very far for a meal. They won't search like they will during a brown drake hatch. I have had the best results fishing my nymphs with a short 2 - 3 inch Al Campbell twitch. I've seen the naturals dart like that.

If the fly hatches in the morning the spinner fall happens around dark or so. Some species have their spinner fall just after the hatch so stay awake. Depending on the species, some crawl down weeds and rocks or dive bomb the water. I generally tie my spinner as a wet fly with a pronounced egg sack and fish it with an indicator downstream dead drift. In the hot summer all these things can happen after dark. I have seen a morning spinner fall in the summer but I've probably missed that act more times than not. The rises are there but a person will miss what is happening. Morning spinner falls are missed by most. A soft hackle can be great then, with a real green butt.

The sad thing is I have faced blanket hatches where I was the only person who was on the hatch. This tends to be a late April or early May thing. Hundreds of thousands of flies and no rises. Single malt Scotch time. I will fish the hatch all year, generally with a 16 - 18 thorax or parachute or a brownish green nymph. Lately I've been trying a 16 nymph with a bright green color. This year I hope to have an answer on the color enhancement and augmented size theory that I believe works.

Remember the olives will hatch at the same place every year, and at the same time generally. In the mid-west it's unusully warm this year.

A soft hackle fly, a green bodied fly with a partridge hackle should be king.

Since this is a year-long event don't forget to carry them. Green is king. Old Rupe

Special credit to: Hatches II by Al Caucci and Bob Nastasi, published by The Lyons Press for the photograph in this article. Drawing from Mayflies by Malcolm Knopp and Robert Cormier, published by Greycliff.

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