Ephemeroptera means ephemeros 'of/for a day', pteron 'wing'. So named because the adults live less than a week.

Mayflies live near water as their young (niaids) live in clean fresh water. Mayflies are a major food source for fish. Fishermen tie fishing flies to look like them.

However, these are NOT flies. They have 2 pairs of wings and no haltares. Their wings have many veins and cannot be folded over their backs. The forewing is well developed and the hindwing is small. Their legs are slender, just for perching not for walking. Their antenna are short and bristlelike. They have 1 to 3 slender cerci (tails) on the tip of abdomen. As an adult they live a short time and therefore do not need to feed. Their mouthparts and digestive tracts are poorly developed.

The niaids are scavengers and predators and may live for years.

They are hemimetabolous (have incomplete metamorphosis).
Mayfly - Callibaetis pictusMayfly  - Baetis sp.Small squaregilled mayfly - Caenis sp