The Often Confusing March Brown
I decided to write this article due to the confusion we often notice when anglers from across the nation
are ordering March Brown Mayflies. The problem is, there are two completely different mayflies in all
respects that have the same common name, March Brown. Unless one specificies the mayfly as a Western
March Brown or an American March Brown, the common names can be confused. To add a little more to the
confusion the common name March Brown is often used for the Western March Brown. The add even more
confusion to the common names, the American March Brown is sometimes called the Eastern March Brown.
This is a perfect example of where scientific names are necessary to make certain one is referring to the
The Western March Brown is usually called the March Brown without the Western designation and is
generally correct. The proper scientific name is
The American March Brown, also called the Eastern March Brown is a Maccaffertium vicarium. They are
also found in the mid-western states. For you old timers, at one time the American March Brown were
classifed as Stenonema vicarium, or plain March Brown and the Stenonema fuscum, or Gray Fox. Some old
hatch charts still refer to these incorrect scientific and common names.
American March Brown
The insects are large enough that it is fairly easy to identify them but at first may cause some confusion
since there is also another insect with the common name March Brown but sometimes called the Western
March Brown. It isn’t even in the same family as the American March Brown and still confuses anglers trying
to select a pattern to imitate it because of the similar names. To further confuse some old time anglers, the
insect was moved from its original classification and was often referred to as the Gray Fox. It was moved
from the Stenonema vicarium and Stenonema fuscum classifications. The American March Brown is the
Maccaffertium vicaruim, a species of the Heptageniidae family. It is a species of the Heptageniidae family.
Click Here to see the Perfect Fly American March Brown mayfly patterns.
The March Brown, sometimes called the Western March Brown is either the Rhithrogena morrisoni or a
less common species, the Rhithrogena hageni. It is in the Heptageniidae Family of mayflies.
March, 2020 Issue
Copyright 2021 James Marsh