Small Mayflies

Family Baetidae

Baetis sp.. Photo:Stephanie Boucher

The naiaids (immatures) have long antennae and long legs and three caudal filaments. They are common in mud of still waters, and in warm shallow and rapid water. They are more tolerant of water pollution than many other mayflies. Baetidae are small, usually less than 12 mm (excluding the tails). The females are usually brown while the males are pale and sometimes have abdominal segments 2 to 6 transparent. The front legs of the male are longer than the others. In both sexes, the front wings are elongated and oval, and the hind wings are very small or lacking. They have only two caudal filaments, ulike many other mayflies, which have three.