Species of the Month

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! 

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. 

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).  

• 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. 

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. 

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.