If you take a dip-net out this time of year, as our canoe guides often do along the Wolf, you can probably pull up the larvae of the mayfly Hexagenia.
Mayflies get their name from the springtime appearance of large numbers of the adult flies.
Mayflies belong to the order Ephemeroptera, which is a particularly apt name for the ephemeral adults. Their sole mission is reproduction, and they die shortly after mating and laying eggs. A larva may be identified by the presence of leaf-like gills along the sides of its abdomen and three caudal cerci, or filaments. Note that these filaments are sometimes stuck together and therefore may appear to be only one. Larvae of the Hexagenia can be collected in sandy sediment with a dip-net.