Ephemeroptera

Ephemeroptera, commonly known as mayflies, is an order of ancient, aquatic insects. Fossil records extend back to the Carboniferous period, making them among the earliest lineages of winged insects. The order comprises roughly 2,500 to 3,000 described species in about 40 families and is distributed worldwide, with the greatest diversity in temperate and tropical freshwater systems.

They spend most of their life as aquatic naiads in streams, rivers, ponds, and lakes. Naiads are typically herbivorous or detritivorous, feeding on algae, detritus, and small invertebrates, and they breathe via abdominal gills. After multiple molts, the final aquatic stage emerges as a winged subimago, or dun, which itself molts to the final adult, the imago or spinner. A distinctive feature of Ephemeroptera is the subimago stage, which is winged but usually dull-colored. Adults usually have two pairs of wings: large, triangular forewings and smaller hind wings, held upright above the body when at rest. They have short lifespans and, in most species, do not feed as adults because mouthparts are reduced or absent.

Ecology and reproduction: Emergence events can be dramatic, with adults swarming over water to mate. After mating, females lay eggs on the water surface or in the water; eggs hatch into naiads, continuing the life cycle. Because mayfly naiads require clean, well-oxygenated water, mayflies serve as important bioindicators of freshwater quality and are commonly used in ecological monitoring. They also play a critical role in aquatic food webs as prey for fish and other predators.