Common blue damselflies (Enallagma cyatherigerum) mating on a water reed. Damselflies may remain in tandem like this for some time - even after mating. They lay their eggs on submerged plants. Widespread throughout Britain, this voracious predator spends much of its life as an aquatic nymph. Damselflies are easily distinguishable from dragonflies when resting - they hold their wings swept back along the body whereas dragonflies hold them perpendicular.