Understand dragonflies and damselflies

From early summer, any small pool will attract dragonflies and damselflies. To identify these insects and observe their behaviour, you need a good pair of binoculars.

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Understand dragonflies and damselflies article spread

From early summer, any small pool will attract dragonflies and damselflies. To identify these insects and observe their behaviour, you need a good pair of binoculars with close-focusing capability or a low-power monocular.

Damselflies in particular are often only distinguished by small differences in their abdomen patterns.

 

Background
 
  • Dragonflies and damselflies both belong to the insect order Odonata and have two pairs of wings. Damsels are smaller and have a lighter build than dragons. When resting, they fold their wings over their backs, whereas dragonflies spread their wings out to the side.
  • Dragonflies are among the fastest and most manoeuvrable of insects. They can fly forwards, sideways, backwards and hover for extended periods; some can even reach speeds of 35kmph.
  • Damselflies are slower (up to 10kmph) and have a more fluttering flight.
  • Both have aquatic larval stages called nymphs, which can take several years to become adults. Juveniles are known as nymphs because there is no pupal stage.
  • Dragonfly nymphs are similar to the adults but lack their colour and wings.
  • Damselfly nymphs tend to hide in sediment or pondweed, and have three gills protruding from the tips of their abdomens.
  • The last nymphal stage crawls out of the water, often by climbing vegetation, and the adult emerges from a split in the cuticle. Dragonfly nymphs can crawl some way from the pond; their exuvia (shed skins) are left clinging to vegetation.

 

Breeding
 
  • Newly emerged dragonflies take a few days or weeks to sexually mature and attain full adult colour. They then return to a pond to mate.
  • Eggs are usually laid in water. There are two strategies: damselflies and hawker dragonflies have elongated eggs that are inserted into small slits made in plant stems; others have round eggs that are dropped directly into the water.
  • Southern hawkers lay eggs in damp mud and moss near pond edges and even in rotten wood.
  • While egg-laying, they vibrate their wings, just in case they need to take off.
  • In territorial species of dragonflies, the female lays eggs on her own, though the male often stands guard nearby. In non-territorial species, particularly damselflies, the male stays with the female to prevent rival males from mating with her.
  • Female damselflies often crawl down plant stems, and so are underwater when laying their eggs. At this point, they are very vulnerable to predation by fish and newts. Males stay above the water to prevent other males from mating with the female and to watch out for predators.
 
Feeding
 
  • At night or in cloudy weather, dragonflies and damselflies rest on pondside vegetation and are often a lot easier to approach and identify.
  • They consume about 20 per cent of their bodyweight each day. They catch other insects, usually small flies and mosquitoes, but larger dragonflies will take butterflies, wasps and smaller dragonflies.
  • Larger dragonflies eat prey on the wing, whereas hawkers and damsels generally perch to eat.
  • All species can also be seen hunting prey along hedgerows and in woods, well away from water.
  • Nymphs possess a mask below the mouth that can be shot out to catch passing prey. Nymphs of some dragonflies can be seen hunting near the surface; others lie buried in mud waiting to ambush passing prey.
 
Territorial behaviour
 
  • In many species of both dragonfly and damselfly, males establish territories and drive away rivals by hawking across the pond, or by taking up a vantage point on the pondside or on emergent vegetation.
  • Males try to grasp the thorax of passing females with their legs; males have hook-shaped claspers at the tips of their abdomens to help them get a firm grip.
  • Damselflies grasp females just behind their heads; dragonflies grasp females on top of their heads. Grooves on the females ensure the males get a good hold.
  • The male’s sperm is in a sac near the base of his abdomen. The female situates herself behind the male and bends her abdomen forward to facilitate sperm transfer, forming a circular shape unique to the Odonata order.

 

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