Lesser Emperor dragonflies were unknown in the UK until 1996, but have gradually colonised the country since then, with global warming the most likely reason. The first definite sighting in the Cotswold Water Park occurred in 2006, however until the last 2 or 3 years encountering this species around our gravel pits was still unusual. That situation has now changed; recording 10 or more in a day is now possible, and their local range is expanding, particularly in the western section of the CWP. On a national basis, they are now quite widespread, but in low numbers. It appears that the CWP may well be the best place in England to see them.
Lesser Emperors are a member of the ‘Hawker’ family of dragonflies, and are big – only slightly smaller than Emperor dragonflies (our largest species). In flight they often appear predominantly dark, with green eyes and a sky-blue band where the thorax (body) joins the abdomen (tail). Closer inspection of perched individuals will reveal the main colour as a rather difficult to define, drab brown grey, with a hint of violet. Males always have the sky-blue band, females are more variable; some don’t have a band, whilst others have blue extending further down the abdomen.
They are a species which breeds in still waters, so are unlikely to be encountered along our rivers. They can turn up well away from water though; when hunting, sheltered areas where insects gather will attract them. They catch a wide variety of insects, including damselflies, or even butterflies. Their breeding behaviour is unusual amongst large dragonflies, as they lay eggs whilst still joined together, ‘in tandem’, with the tip of the male’s abdomen attached to the back of the female’s head. I have seen several pairs joined together, with the female egg laying, on the Cotswold Lakes Trust Cleveland Lakes Reserve this summer – so it looks like the population is set to expand yet further.
Kim Milsom, Biodiversity Field Officer, Cotswold Lakes Trust