By James Duncan
Learning and Engagement Officer
The flying insects that make up the order Odonata are without doubt one of the most successful groups of animals that exist on the planet. Their ancestral lineage (in the form Meganisoptera) dates back more than 320 million years, putting them on Earth significantly prior to the arrival of the all-conquering dinosaurs. The modern-day forms exist predominantly as either Dragonflies (Anisoptera) or Damselflies (Zygoptera). Observing these magnificent aerial predators may well be one of the most wonderful things in nature. Typically the first species to be spotted in spring is the rather stunning Large Red Damselfly (Phyrrhosoma nymphula). Their long-term success is largely due to one key factor - they're superb hunters par excellence, perfectly adapted for purpose and surprisingly unchanged (physiologically) since prehistoric times. Most display capabilities in flight that would shame a modern fighter jet. When combined with superb eyesight, courtesy of their oversized compound eyes, there's little prey that stands a chance. Of course, they're also wonderfully adaptable, living in habitats ranging from freshwater lakes to muddy, stagnant, acidic pools.
It's possible to split the two orders without too much difficulty - Dragonflies are typically larger and fuller-bodied, their eyes meet (in the majority of species), they hold wings at right angles to the body at rest and they exhibit a powerful, dashing flight with bouts of hovering. Damselflies on the other hand are daintier, have eyes that are separated, typically hold their wings over the body when rested (as a general rule) and tend to have a fluttery, more Butterfly-esque flight. If you happen to have a pond in your garden, this will undoubtedly be the perfect time to spot a Large Red Damsel, particularly as it's one of the most widely distributed species in Britain. It can only really be confused with the much rarer Small Red Damselfly, though its habitat preferences are less fussy and its black legs distinctive. They can be spotted any time between the start of spring and late summer and now's a great time to look for freshly emerged adults, through the discovery of an exuvia. This is the evidential exoskeleton left behind after moulting from an underwater nymph to aerobatic adult, a process known as ecdysis. Fresh emergents are known as tenerals, though identification in this stage can be tricky - colour pigmentation is lacking and sexes look similar, a time where the body and wings gradually begin to harden in the lead up to sexual maturity.
The 'red' and 'blue' families of Damselflies are quite unusual in that it's only really the females that exhibit variation in colour, a phenomenon known as colour polymorphism. The Large Red Damselfly has three distinct female colour forms. This would seem unusual considering it's typically males that need to attract a mate. However, there's little in nature that doesn't serve a purpose and studies have indicated this may be an evolutionary response to allow dynamic adaption to changing ecological conditions. Variation aside, all colour morphs are unmistakable and bring a beautiful splash of colour to quiet bodies of still water at this time of the year. Like many others species, the large red damselfly males are distinctly territorial and will clash in bouts of aerial combat with not just males of the same kind, but any insect that dares to pass close by.