Maccaffertium sp.
FLAT-HEADED MAYFLIES (Heptageniidae)

Description
This mayfly is all white on the head, eyes and body and is about one inch or 25 mm in length. It has very long, thin white cerci (“tails”). The wings are hyaline with blackish vein markings. The males have dark eyes. The name Flat-headed Mayflies refers to the nymphs which are flattened and streamlined. This mayfly was identified by volunteer experts at the BugGuide website.

Occurrence
The frequency of occurrence in Fontenelle Forest and Neale Woods is not known. One female has been photographed in Fontenelle Forest on Missouri Trail in early October 2012. This is one of the later mayflies that flies from late May into October.

Comments
The larvae of Maccaffertium mayflies are not as oxygen and temperature sensitive and are more tolerant of pollution than other mayflies. This gemus is a favorite among fly fishermen who call them Cream Cahills.

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