The way
it works is that one need not enter anything at
all to perform a lookup. Of course, that would
result in listing all genera. However, any
observation one is able to enter eliminates some
genera. Let's look at a version of the 2nd
photo, which I have annotated:
From the photo, it is apparent the mayfly has 2
tails, fore wings of uniform color (hyaline),
and minute hind wings. Also, it was
described as having a body length excluding
tails of 1 cm. (10 mm.)
By entering only the following 5 pieces of
information:
Number of tails = 2
Body length = 10 mm.
Fore wings = uniform color
Hind wings = minute
Geographic location: Italy (IT)
the genus is narrowed down to
Baetis:
If you then click on
Baetis (on the query results screen), it
takes you to an extremely detailed listing the
N. American
Baetis species. I believe you will find
the mayfly pictured is extremely similar to the
N. American species
B. bruneicolor.
I say this because it is the only species that
reaches a length of 10 mm., and because it has
very dark abdominal tergites 1, 7-10.