About the Mayfly
Order Ephemeroptera, Classes Schistonata and Pannota
The mayflies have several other common names, depending on where they are found, and what stage they are in their life cycle, including: mays, upwings, duns, spinners, dippers and fish flies. They are not a particularly important food source of fish in British Columbia. Mayflies in this province are smaller and less numerous than most mayflies in the rest of North America.
What does the mayfly look
like? The most distinctive feature of the mayfly is its tail. Adult mayflies are a winged insect with two or three long, thin tails extending from the back of their abdomen. Their wings are partially transparent. Most mayflies are reddish brown, brown or slate gray, but some are lime green. Their bodies have a slightly flattened appearance because of the row of gills along the sides of their abdomen.
The pupal mayfly is most noticeable when it is resting on the surface of the water, waiting for its wings to dry after emerging from the lake. In this position, they appear very triangular in shape.
Where does the mayfly live?
Mayflies are found all over the continent and everywhere in British Columbia, although their numbers are relatively low here. They require oxygenated and unpolluted water, which may be flowing or still. They are common in freshwater habitats worldwide.
Food for Thought… The use of gasoline boat engines on lakes will reduce mayfly populations. This has only a small affect on the fish in British Columbia, because they do not appear to be an important food source for fish here. But what other effects might it have?
What is the life cycle of the mayfly?
Mayflies swarm and mate in flight.Click here to see the life cycle of a mayfly. The males bob up and down in the air - which is why they are sometimes called "dippers" - while the females fly straight through the swarm until seized by a dipping male. The female lays her eggs while skimming over the surface, or sometimes she will dive like a submarine and lay them in the bottom weeds. The eggs hatch into a larva or nymph which hides on the lake bottom, sometimes burrowing into the mud. Nymphs grow and then transform into a pupal form called a "sub-imago," which surfaces, dries, and then transforms into an adult.
- Mayfly nymphs usually mature in about four weeks, but some species can take up to four years to become adults.
- Most mayfly species have no mouthparts and cannot feed, so they live a very short time, usually only a day or so.
Did you know that . . . Mayflies are the only living insects that molt again after they have wings.
Often the mayfly sub-imagos are called dons. As they are very vulnerable to predation while their wings dry, they make up an important part of a fish's diet. Once they mate and die, they are often found floating on the lake's surface. These dead adults (or spinners) are also important fish food.
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