Tom Kysilko pds at VISI.COM
Fri Jun 15 01:42:54 UTC 2001

At 11:02 PM 6/13/2001 -0500, I wrote:
>My cousin is a bug specialist at the LaCrosse WI DNR station.  I'll see if
>she can shed any light.

As promised:

"Fishfly" is a generic common name which can apply to various types of
aquatic insects, but it is MOST COMMONLY used in the stretch of river
mentioned in the quote you sent below as a synonym for big river mayflies
(Ephemeroptera).  Hexaginia bilineata is the genus and species of the big
river mayfly.  Some of their relatives, very similar in size but paler in
color, Hexagenia limbata, are often mixed in with swarms of H. bilineata,
but usually not in such large numbers.  H. limbatalarva can inhabit lakes
and tributary streams, whereas H. bilineata larva usually are  limited to
very large rivers such as the Mississippi.  "Fishfly" is used in the
vernacular as a collective term covering both species.  As the dictionary
mentions, it can also be used to refer to insects in other aquatic orders,
but not commonly in the upper Mississippi valley.  "Fishfly" means "big
mayfly that swarms" there, I think.

Glad I could help out. You have fufilled my annual goal of enlightening at
least 1 public entity about mayflies at this time of year--a common time
for media interviews on the topic.

J. Terry Dukerschein
WDNR Mississippi River Resource Trend Analysis Field Station

  Tom Kysilko        Practical Data Services
  pds at       Saint Paul MN USA

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