I am tempted to ask what you think is most important, size, shape or color? But, my question is this. Dead drifting nymphs is a common practice. Is there a certain hatch where giving your nymph movement but slightly tugging on the line is an advantage?

In the upper midwest we get hatches of pale yellow may flies in June. They are about size 14-16 and we call them sulphurs. On western rivers what looks like the same thing are called pale morning duns (PMDs). Same basic thing or something different?

Parachute Adams! I love it that you are such a complex "Bug Guy" , but, when it boils down to it, you picked a classic fly to use. Oh, and nice hair!

Buckmaster: While a perfect dead drift is generally the most effective presentation for both drys and nymphs, there are those days on the water when "twitching" your flies can produce outstanding results. Having said this, I personally do not know of a way to determine when putting movement on your fly is the way to go. One simply needs to give it a try and see if fish will respond to this type of presentation. I had days on the water when twitching a grasshopper imitation was deadly.

Yes, some days you twitch and they strike, others you twitch and they run. Thought the twitch may have been related to certain bugs.

And it's buckhunter, not buckmaster. "Master" sounds like I'm bragging, though have had a couple deer featured in the magazine.

Koldkut: First off, remember that the only major un-damned river (not a tail water) in the entire Continental United States is the Yellowstone......Something to ponder in and of itself! The simple answer it that because flow regimens as well as temperature can vary wildly below an impoundment area the natural course of aquatic insect development can potentially be heavily impeded. There are some species that flourish in this type of aquatic environment and others that are eradicated completely. Water can remain at unnaturally high or low flows for extensive periods of time. Additionally whether a damn releases water from the top or the bottom has major ramifications as far as temperature. Temperature is the single most important factor when it comes to the overall health and biodiversity of a river for both aquatic invertebrates and well as fish. This is not to say that larger insect to not occur directly below tail waters; they just may simply be lower in overall biomass. The low water temps especially directly below dams, inhibits both fast and large growth of aquatic insects. Because midges have a high tolerance to the perturbations that are caused by damns, they are often very successful in these types of aquatic environments. Another great example is BWO's and Trico mayflies....they are pretty tough relatively speaking and consequently often thrive in these conditions. While this is a generalization, I have noticed in my many years of collecting aquatic insects that there "seems" to be proportionally higher populations of "larger" insects the farther down river one moves away from the actual damn, although I cannot support this assertion with any quantitative study.
THE BUG GUY

This has been very informative Mr. Younghanz. Thanks for taking the time to answer some questions.

On so many trout rivers, there are a vast number of mayflies, caddisflies, stoneflies, and other aquatic life (like scuds) all living together. Do they all get along down under the surface or are there some serious turf battles going on? I think what I'm really asking is are there certain aquatic insects that never hang out with certain other insects on the same rivers or sections of rivers? In other words, if I see type X mayfly hatching in a river this spring, for instance, I won't see type Y mayfly hatching any where near there.

Bug Guy, I am please to read your answer to dleurquin. Have scratched my head a few times while buying flies away from home. Thought I was crazy but I guess I'm just regionally challenged.

Thanks for the great answers.

Okay. I just reread the last part of my last question and it didn't sound very clear. Hope this is a little better. Bug Guy, my question is about whether there are certain aquatic insects that avoid each others' territories. What I mean to ask is, if I see mayfly (or aquatic bug) "A" hatching in a section of river, are there any bugs I won't see hatching or hanging-out in the same area as mayfly "A"?

And if Robert can put the entire package together from easy to understand bug development, and then relating it to flyfishing he's got something. Most, like Robert's scientific background, make it borrrrring providing to much scientific info on the bugs, and not how it relates to fly fishing...What flies to use by what you see happening. The thought process involved. Many times it can be what you do not see as an approach to what fly you might choose. And back to Koldkuts question as to why not big bugs in tailwaters, and SpringCreeks..sometimes there are some bigger bugs but the bottom structure, the need for bigger rocks, and the bank vegetation (riparian zone) can also be a factor as well as the need for temperature variation. Usually MORE of what they have, but less of a variety of bugs in tailwaters, and Spring Creeks.