Arthrop/Insecta/Eph/heptageniidae.htm
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ORDER: Ephemeroptera
FAMILY: Heptageniidae
This family of mayflies can be characterized by their distinctly flattened heads and striking resemblance of the character 'Jack Skellington' from the movie 'The Nightmare Before Christmas.' This family can either have two or three cerci (tails).
Commonly encountered genera include Epeorus, Heptagenia, Maccaffertium, and Rhithrogena.