Here today, gone tomorrow

The wet winter and warm spring have meant that insects which have an aquatic nymph stage have had a great season – think mosquitoes. Another such insect is the Mayfly (pictured left). Living most of its lifecycle (years) as a nymph the lifetime of an adult mayfly is brief – measured in hours. This stage of the lifecycle is so small the insect has no need to eat and therefore the adult has no mouthparts. When the conditions are right (i.e. now), mayfly nymphs leave the water en masse, emerge from their sub-imago state and in the time they have left, mate and then die.
 
 
The nymphs live in clean water environments and feed on underwater vegetation and detritus. Over the period of months/years they progress through several moulting events before they emerge from the water after the final moult as a sub-imago. The sub-imago (pictured right) is sexually immature and does not have the colouration of the sexually mature adults. After a couple of days the adult mayfly ‘hatches’. The pictures below show various stages of the adult emerging.
 
 

Mayflies are of the same order as Damselflies and Dragonflies and look similar. However there are some characteristics by which you can tell the difference. They have two pairs of wings but one pair is much smaller than the other. At rest the wings are folded over the back like most damselflies. Male mayflies have very long front legs. These are used to grasp the female in flight so that airborne mating can occur (Fly United indeed). Extending from the back of the insect are three filaments. The outer two are called cerci. A lot of insects have cerci. In mayflies they are sensory organs. In insects such as earwigs they form defensive pincers.
 
 
 

It is the head of the mayfly that is most distinctive. Like their related cousins, the dragonfly and damselfly, mayflies have a pair of compound eyes and three ocelli (a set of simple eyes thought to detect light and dark and therefore help an insect fly level). In addition the adult mayfly has two huge ‘turban eyes’ mounted on the top of the head. These eyes detect ultraviolet light and are thought to assist in the detection of females flying overhead.

At this time of the year adult mayflies can be found in their thousands resting on aquatic vegetation and flying above the water looking for mates.

Live fast, die young – the mayfly motto.