Mayflies have 2 adult stages. The first is the pre-adult stage known as the ‘dun’ when the brown-coloured winged form emerges from the water. The second stage is the full adult form known as the ‘spinner’. The ‘spinner’ has a creamy-yellow abdomen with distinctive dark triangular markings, translucent, dark-veined spotted wings and three long tails. Females are slightly larger than males with males having a pair of pincers near their tales.

From May to August large swarms of male Mayflies gather to perform an elegant dance in an effort to attract a mate. The female Mayflies fly into the swarm and choose a mate. Females dip their abdomen into the river and lay their eggs which fall to the riverbed. They hatch into nymphs which spend nearly 2 years in this state before emerging as adults and restarting the cycle.

Mayfly nymphs feed on the Algae found in the streams and ponds on Brimpts Farm. The adult Mayfly has no functioning mouth part and therefore is unable to feed, their primary function is to breed. Mayflies are found from May to August swarming over the river and can be best seen on a bright day. They make a valuable food source for the Pied Flycatcher, another species which can be seen in the woodlands at Brimpts. Mayflies are very sensitive to pollution and their larvae in a stream or pond indicates clean water.

Mayflies are older than the dinosaurs. They were the first winged insects to evolve and there are fossils dating back more than 300 million years.