Flat-headed Mayfly Nymph

Statistics

Taxonomic order: Ephemeroptera

Taxonomic family: Heptageniidae

Length: up to 2 cm

Average life span: 1 to 2 years

Juvenile stage (in water): up to 2 years

Adult stage (out of water): 1 day

When To See

All year round.

Photo credit: lifeinfreshwater.org

Habitat

Freshwater habitats including lochs, ponds, wetlands, and flowing waters of streams and rivers. On the surface of rocks and submerged logs. When disturbed, they quickly hide themselves under stones. Their flattened bodies and strong legs spread to the sides help reduce drag of the current, allowing them to move even in fast flowing sections of streams.

How To Identify

Flattened body and head, legs spread to the sides and each one ends with a single tarsal claw. Gills are rounded or leaf shaped and attached to the abdominal segments. At the end of the body are three filaments covered with short setae (hair-like bristles).

Seen It?

Been kicking about in your local river and come across one of these invertebrates? Not sure? Share it with us at trust@forthriverstrust.org, we enjoy chatting about inverts with you.