Tom H.
Klubertanz
University
of Wisconsin - Rock County
Baetisca
lacustris McDunnough. Found in high-quality streams. One of the
coolest of all mayflies. The carapace over the back is speckled with
brown.
Heptagenia diabasia
Burks. This is one of the most common mayflies in southern
Wisconsin. It belongs to the Family Heptageniidae, recognized by the
flattened head and dorsal eyes.. 
.
Tricorythodes sp. (left) and Caenis latipennis Banks (right). They may look alike, but really they are quite unrelated. Both are sluggish mayflies found crawling through debris from ponds and streams.
Ephoron album (McDunnough). There are a handful of families of
"tusked" mayflies. The tusks are formed from the mandibles and
are used to help the insect burrow in silt and mud.
Hexagenia limbata (Serville). As you can see, this is another of the "tusked" mayflies. The adults of this mayfly are large and generally yellowish. A related mayfly, Hexagenia bilineata, is the species known for forming huge swarms along the Mississippi River.
Click here for original image
Ephemerella needhami McDunnough. Ephemerellids as a group prefer high water quality. The two rows of dorsal tubercles found along the abdomen, just inside the margins of the plate-like gills, are found on many members of the Family Ephemerellidae.
Pseudocloeon propinquus (Walsh). This is the upper lip, or labrum, of a mayfly species common in the Upper Midwest. This mayfly and several other closely related species have been re-classified several times in recent years. For a long time, they were placed in Baetis. More recently, they were in the genus Labiobaetis. In North America, the name Pseudocloeon has a long history and once included many mayflies now transferred to other groups. All of this shows how frequently workers reconsider their own theories, trying to make sense out of extraordinarily complicated and confusing data. The problem, of course, is that so many of these mayflies look very much alike. The best way to identify Pseudocloeon propinquus, for example, is to examine the pattern of hairs on the labrum.
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here for original image
Fallceon quilleri (Dodds). This species has been one of my favorite mayflies for a long time. They are active swimmers, shaped like minnows, and in Iowa and Nebraska they usually have a pale stripe down the back of the thorax and abdomen. The photo below is a mandible, with features diagnostic for Fallceon.
Baetis tricaudatus Dodds. This is a phase-contrast photograph showing the setation on the antennae, a helpful character for differentiating this species from related ones.
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here
for original image
This photograph shows numerous mayfly skins (exuviae) on a velvetleaf plant. Mayflies are the only insects that molt from one winged stage to another. In all other kinds of insects, the winged adult does not molt and does not increase significantly in size.
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here for original image
Please feel free to contact me via Email at
tklubert@uwc.edu
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