Mating Success and Larval Aggression

Male Large Red Damselfly, Pyrrhosoma nymphula

The Large Red Damselfly (Pyrrhosoma nymphula) is the only red bodied damselfly to be found in Ireland, something that makes identification of the adults quite easy. They also seem to be the most friendly: the individual pictured landed on my shoulder just after I had taken its photograph. However, like all other damsel- and dragonflies, the Large Red Damselfly spends the majority of its life as an aquatic nymph. This means that this stage of its life is the most important for mating success as an adult. Larval P. nymphula are territorial predators (1), generally found in acid water such as shallow bog pools and small oligotrophic and mesotrophic lakes. Due to the frequency of such habitats in Ireland, P. nymphula is one of the most widespread and frequently recorded damselflies in the country (2). During the nymphs four instar stages, it is feeding during the first three that determines the size in the last stage, and ultimately the size of the adult. Larger males have been shown to win more territorial disputes and thus obtain more mating events near water (1). So therefore the territorial aggressiveness of larval P. nymphula enhances short-term mating success in the adult stage.

References:

1. Harvey and Corbet, 1985. Animal Behaviour 33 pp. 561-565
2. Nelson and Thompson, 2004. The Natural History of Ireland's Dragonflies pp. 154-160