The Stream Doctor

June 13th, 2005

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. Are the hatches of northern Rhode Island much different in color than the hatches of northwestern Wyoming and southwestern Montana?

A. Thanks for the additional information that you sent me - that you were referring to both species and color of mayflies and caddisflies, and that most were brown in New Hampshire and green in Rhode Island.

Even with the additional information, answering such a general questions is nearly impossible. Bear with me while I do some stage setting. I dug out some pertinent numbers from various references in my library and found that there are approximately 14 families and 45 genera of mayflies, and 19 families and 87 genera of caddisflies in the northeastern US. Since there are usually more than one species per genus, you can readily see that we are talking about 45+ species of mayflies and 87+ species of caddisflies.

Now, how about Montana? One outdated (1974) survey stated that there are over 200 species of caddisflies in Montana, with about 70 species in Yellowstone NP. Comparable numbers for mayflies are 100 species in Montana and 40 in YNP. Now to put the whole thing in context, there are over 700 species of mayflies and 1,350 species of caddisflies in North America. Are you beginning to see the difficulty in responding to your question without knowing what species you are referring to? Believe me, I am not trying to belittle your request but am trying to show how such a general question begs an accurate answer.

But, that doesn't mean I won't try to respond in similar generalities. First, concerning color. I would hazard a guess that you can find hatches colored brown, tan, green, cream/yellow, blue/gray, and shades between if you were to make a thorough survey of hatches in your region. And, not surprisingly, the same colors occur in Wyoming/Montana - and just about anywhere else you look. Whether the same species differs in color between the two regions is beyond what sources I have to study. What I'm trying to say is that adults of these two orders of insects pretty much occur in all common colors. Now, this begs the question of whether the same species is the same color in both regions, but I'd be surprised if there was a significant difference.

Remember, also, that distributional patterns of insects follow some generalities. By-and-large, families occur over broader ranges than genera, genera ranges exceed species, and species have the most restricted distribution - even though some common species can occur throughout the US or even more widely. This tells us that the more refined your identification of an insect, the more it might have restricted morphological characteristics, such as color. Thus, if you were able to name the species you are concerned with (note: species is both singular and plural), I might be able to determine if it occurs in both regions and check with some local entomolgists/ecologists as to color phases present. ~ Bert

If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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