larvae are called nymphs. They generally have three tails (anal circi),
gills on their abdomen, and only one claw on each leg. Nymphs may molt as
many as 50 times, although most do not do it that often. Breathing takes
place with the gills, which, in some species, can be moveable or able to
vibrate. This increases the amount of water moving over them to aid in oxygen
In some species, the nymph may mature within a few months, while in others maturation can take up to two years. During this stage, the mayfly under goes metamorphosis, changing its structure to that of the adult with flying wings. Most nymphs live in the aquatic vegetation or among dead leaves and vegetation, but some can burrow into substrates. Some cling to undersides of rocks to prevent being swept away by the stream. Although some nymphs are omnivorous, most are herbivores feeding on algae, diatoms, and detritus.
|Emerging from the nymph is the dunn. It looks like an adult, having wings. It differs from the adult in the fact that it has very small hairs on the wings. It flies to a nearby tree or bush to harden its skin and dry its wings. This could take 1-2 days.|
goal of the adult stage is merely to mate. This stage can last from a few
hours, to a few weeks. The adult cannot eat because it does not have functional
mouth parts or a digestive system. All of its nutrients must come from food
stored during the nymph stage.
Mating takes place by the male using his legs to attach to the female. They copulate and the male flies off to die. The female then flies to the water and places her eggs on the surface. After depositing her eggs the female dies, or is eaten by a fish. Anywhere from 2,200 to 8,000 eggs may be produced.
If many mayflies are
found in a stream it could be a sign that the stream may be eutrophic.
The nymph thrives on the extra nutrients created by eutrophication and
algal overgrowth, which is caused by sewage, manure, and fertilizers.
By feeding on these substrates, though, the mayfly also aids in removing
them and returning them to the terrestrial environment. Through respiration
they release carbon back to the air and phosphorous and nitrogen are taken
in to their bodies from their food source (leaves and algae).