Baetis spp.

Description
Baetis spp. are mayflies belonging to the family Baetidae. Adults have one or two sets of wings (depending on species) that align vertically above the body while at rest. Adults have two long tails off the end of the abdomen and short antennae. Males have large eyes used by swarming males to find females. Females do not have large eyes. The mouths of adult mayflies are nonfunctional and most live for only a few days after emerging. Baetis larvae are aquatic herbivores that drift downstream in search of food. The typical diet of Baetis larvae consists of algae growing on the surface of rocks.

Habitat
Nymphs (larvae) are generally found in well oxygenated rocky bottomed streams. Adults are terrestrial and can be found near water. After mating, adult females lay their eggs under large rocks protruding from the surface of the water in fast flowing stream reaches.

Adaptations
Nymphs have gills along their abdomens that are used for obtaining oxygen from the water, and single claws on each of their six legs that help them adhere to rocks. Baetis larvae are excellent swimmers using short, rapid bursts by flexing their abdomens. Adult males have elongated forelegs and claspers, which are used to hold onto a female while mating.