Mayfly

Cloeon dipterum

This small reddish-brown mayfly species is found near Hainault Lake and the forest ponds from May to October. It measures 5 to 7 mm in length and has a wingspan of 13 to 15 mm. Females possess lateral apposition eyes, which are a type of compound eye adapted for daytime vision and provide high spatial resolution over a wide field of view. Males have additional turban-shaped structures in their eyes. These superposition eyes are well-suited for low-light conditions, and it is believed they enable the males to locate isolated females during mating swarms. Their aquatic larvae, referred to as 'nymphs' or 'naiads,' feed on algae and detritus in ponds. Adult mayflies do not feed, and their brief existence is solely for mating. The lifespan of adult mayflies is notably short, typically ranging from 24 to 48 hours, with some species living for just a few hours, and certain females surviving for less than five minutes.