BEHAVIOUR IN FOCUS H
aving spent two years as aquatic larvae, or nymphs, banded demoiselles live only a few weeks as winged adults. Reproduction is now their top priority. During mating, the male uses claspers at the tip of his abdomen to grasp the female behind her head tightly enough to resist the attempts by other males to dislodge him – they are now said to be ‘in tandem’.
If the pair manage to avoid any interlopers and settle, the male flexes his abdomen to encourage the female to loop her abdomen round to interlock with him, forming the ‘wheel’ position. The male removes any sperm that the female has already received, then inserts his own.
Mating lasts less than five minutes in banded demoiselles, though can take longer in other damselfly and dragonfly species. Afterwards the pair separate, but the male guards the female from rivals while she lays her eggs. The female pushes these into plants in the water, so searching for patches of emergent vegetation in slow-flowing waterways is often the best way to spot this fascinating behaviour.
O Brian Walker is a trustee of the British Dragonfly Society: www.britishdragonflies.org.uk
This section between the damselfly’s head and abdomen houses the massive muscles that power its wings. The thorax is a very robust, rigid structure with internal bracing to withstand the forces exerted by the muscles. Male demoiselles are territorial...