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Emergence

Photograph © A. Holt

This sequence shows the emergence of a Southern Hawker. This is a common species found emerging from many garden ponds. The photographs below show the same species and describe the process in more detail.

Photograph © W. Davies

When the final instar larva is ready to emerge it sits near the waters edge where it stops feeding and starts to breathe air. The larva then climbs up emergent vegetation or indeed any object that will take it out of the water, sometimes walking many metres from the water before finding a suitable emergence support. Here whilst clinging to the support with the claws, the body fluids are redistributed forcing the upper adult body to burst out of the larval skin or exuvia.

Photograph © W. Davies

A subsequent resting phase then allows the adult legs to harden. This will then enable the dragonfly to reach forward, grip the exuvia and pull the abdomen free.

Photograph © W. Davies

Again the body fluids are redistributed to inflate the wings and extend the abdomen, the latter being assisted also by the gulping of air.

Photograph © W. Davies

And finally…

The expanded wings now harden and the insect dries out losing considerable body weight before the first flight. The whole process takes between 1-3 hours depending upon the species.

But sometimes things go wrong….

During emergence the dragonfly is very vulnerable to predation so emergence usually happens under the cover of night or early in the morning. Despite such precautions mortality rates are high and in addition insects are often damaged by rainfall, wind or obstacles preventing successful expansion of the wings or body. Some species that emerge early in the year such as Broad-bodied Chaser do so on mass within a short time period whereas others emerge over a far broader time period throughout the summer.

Azure damselfly showing significant damage to wings and abdomen.
Photograph ©  M. Randall