Species of the Month: Emperor dragonfly
Take part in our wildlife survey
Have you seen our Species of the Month in Dorset? By reporting your sighting below, you can help us to build up a picture of the state of Dorset’s wildlife. We send the records of your sighting to DERC (Dorset Environmental Records Centre) who collate this information, providing the opportunity for local naturalists, conservation organisations and wildlife enthusiasts to work together to protect wildlife in Dorset. What’s more, when you complete our Species of the Month survey, your sighting will display on our interactive map below. This allows us to visualize the range of wonderful wildlife our supporters have spotted in their gardens, on their balconies or in their local green spaces throughout the year! So please help us help wildlife by filling in the form below. Thank you!
Species of the Month: Emperor dragonfly
Scientific name: Anax imperator
Layers
Identification
The impressive emperor dragonfly, at around 78mm in length, is the largest of our dragonflies. Males are pale blue, with an apple-green thorax and a black stripe running the length of the body. Females are similar, but a duller greeny-blue.
Emperors have large green/blue eyes which provide almost 360-degree vision.
Emperors can be distinguished from other hawkers by their size, and that they often fly with their abdomen bent slightly downwards – a bit like a flying banana!
Diet
Emperor dragonflies hunt a range flying insects – including other smaller dragonflies.
Emperor larvae will eat anything smaller than themselves, including tadpoles and small fish.
In return, emperors make a decent meal for birds such as hobbies, and their large, juicy larvae are eaten by frogs, toads, newts and fish.
Behaviour
Emperor males are highly territorial and aggressively defend their territories from other dragonflies. They can be seen between April and September, peaking in numbers from May to August.
Emperors mate in flight and the female lays her eggs in floating pondweed.
Emperors live underwater as larvae for one to two years. Once large enough, they crawl up the stems of aquatic vegetation and out of the water. In one of nature's amazing transformations, they then ‘break out’ of their old larval skin and fly away - leaving behind the empty exoskeleton (exuvia).
Did you know?
- The emperor dragonfly belongs to the family of Aeshnidae, commonly known as the 'hawkers', who all hunt and eat their prey in flight.
- Large eyes, powerful toothed jaws and four wings, which are capable of independent movement, make dragonflies incredibly manoeuvrable and efficient predators.
- The adult emperor may live for a couple of months or more, but it'll spend around ten times longer living underwater as an aggressive predatory nymph.
- Dragonflies evolved around 300 million years ago, long before dinosaurs! Due to higher levels of oxygen, these dragonflies reached huge proportions with a wingspan as big as an eagle.
- Emperor dragonflies can reach speeds of 30mph, flying higher and further than many other species, they patrol their territories almost endlessly.
Where can they be found?
Emperors prefer large ponds, lakes, canals and slow-moving rivers, particular those with abundant submerged and floating vegetation.
Their distribution has greatly increased since the 1990s and emperors are now found across most of England and Wales. Due to our warming climate, emperors have been recorded in Scotland since 2003, and can now be found on the southern and eastern coasts of southern Scotland.
How can I help?
These stunning insects need water throughout their lifecycle. You can help by digging a pond for them to breed in. Although, emperors prefer large ponds, a small pond can still provide a source of food.
Submitting your records to ‘species of the month’ will display your sighting on the Dorset Wildlife Trust interactive map. You might also like to record your sightings on the British Dragonfly Society website. Data is used by scientists to monitor population numbers and can help them understand the reasons for any changes.
Report your sighting
Help us build a more accurate picture of Dorset's wildlife by completing this form. Your records will be sent to DERC on the understanding that the information provided by the recorder will be entered onto a computerised database and may be used for nature conservation, research, education or be available to the general public. Your sighting will also appear on our Species of the Month map. You can change your communications preference at any time by contacting us on 01202 692033.
When you have completed the form, click the Submit button. Please note that once submitted it can take up to an hour for your sighting to populate the map.