Heptageniidae

The Heptageniidae (synonym: Ecdyonuridae) are a family of mayflies with over 500 described species mainly distributed in the Holarctic, Oriental, and Afrotropical regions, and also present in the Central American Tropics and extreme northern South America. These are generally rather small mayflies with three long tails. The wings are usually clear with prominent venation although species with variegated wings are known. As in most mayflies, the males have large compound eyes, but not divided into upper and lower parts (the group is sometimes referred to as flat-headed mayflies).