Emperor Dragonfly

The emperor dragonfly is among the largest dragonfly species found in Europe, North Africa and parts of the Middle East, and it is easily recognised by its size, powerful flight and vivid colouring. It belongs to the hawker family (Aeshnidae), a group known for large eyes that meet at the top of the head, long slender abdomens, and near-constant flight while hunting.

Males are famous for their bright, almost electric blue abdomen topped with a black dorsal stripe and an apple-green thorax, making them one of the most conspicuous dragonflies over garden ponds and lakes in summer. Females and immature males are typically green or brownish rather than blue. As adults, both sexes are formidable aerial predators, snatching other flying insects directly out of the air.

Emperor dragonflies play an important ecological role both as predators that help control populations of flies, midges and other flying insects, and as aquatic predators in their nymphal stage, where they hunt small aquatic animals in ponds and lakes.

• Very large dragonfly with a long, slender abdomen and a wingspan approaching 11 cm
• Males: bright sky-blue abdomen with a black stripe running down the centre, apple-green thorax
• Females and immatures: green or olive-brown abdomen, sometimes with a blue tint near the tip
• Large compound eyes that meet broadly along the top of the head, typical of hawker dragonflies
• Clear, unmarked wings held out flat at rest (dragonflies do not fold their wings)
• Powerful, continuous flight with the ability to hover, dart and fly backwards
• Distinguished from similar hawkers by its size and the unbroken black stripe on the male's blue abdomen

Emperor dragonflies favour large, well-vegetated ponds, lakes, canals and slow-flowing rivers with plenty of open water for patrolling flight and submerged or emergent plants for egg-laying. They are widespread across southern and central Europe, North Africa, and the Middle East, and their range has expanded northward in recent decades. Adults are on the wing from late spring through late summer, with males frequently seen defending stretches of open water over ponds and lake margins on warm, sunny days.

Adult males are strongly territorial, patrolling a chosen stretch of water in fast, sustained flight and chasing off rival males, while pausing occasionally to hover in place. Both sexes hunt on the wing, catching flies, midges, butterflies, and other flying insects in a basket formed by their spiny legs, then often consuming prey while still in flight. Mating takes place in flight or perched near water, after which females lay eggs alone, inserting them into the stems of submerged or floating plants while hovering low over the surface. The aquatic nymphs are voracious predators that ambush tadpoles, small fish, and other aquatic invertebrates using an extendable hinged mouthpart, making the species a significant predator both above and below the water's surface throughout its life.

Eggs are inserted into plant tissue in or near water and hatch into aquatic nymphs that live and hunt underwater for one to three years depending on climate, passing through numerous instars in an incomplete metamorphosis with no pupal stage. Mature nymphs climb out of the water onto emergent vegetation, where the adult dragonfly emerges from the nymphal skin (exuvia) in a process that can take several hours, followed by a period of hardening and colour development before the first flight. Adults typically live for several weeks during the warmer months, with one generation completing over one to three years due to the extended aquatic nymph stage, and the species overwinters as a nymph in the water.