In this article, Dougy Wright, warden of Windmill Farm Nature Reserve on The Lizard, explains how to tell three related species of dragonfly apart: the Emperor, the Lesser Emperor and the Vagrant Emperor (a rare migrant). All three species have been seen at Windmill Farm. Dougy first wrote this article as a blog post on our website, published in October 2019.
The Vagrant Emperor: a migratory dragonfly
It may seem odd to be writing an article about dragonflies on The Lizard in autumn. However, there are still some on the wing and, furthermore, there is a chance of a particular dragonfly species in any month of the year. About 10 years ago, a friend of mine (Andy Pay) found three Vagrant Emperors (Anax ephippiger) at Windmill Farm: these were the 18th, 19th and 20th records nationally. Since then, Vagrant Emperor sightings have become more common – though still rare. I have seen 14 individuals at Windmill Farm – seven of which were this year (two of them in October).
So when is the best time to look out for these wonderful insects? Vagrant Emperors are a migratory species and can travel long distances – they mainly reside in sub-Saharan Africa and the Middle East. The most likely time they might travel our way is when we have had a period of strong southerly winds, and they can appear at any time of year They are about 6 cm long; generally, the body is beige/brown in colour with a blue patch on the second segment of the abdomen (the part of the dragonfly behind the wings). The eyes are brown.
Emperor and Lesser Emperor dragonflies
The most likely species that you might confuse with the Vagrant Emperor is the Lesser Emperor (these are rare on The Lizard – in fact I have only seen three of these at Windmill Farm). Lesser Emperors are slightly bigger (7 cm) with green rather than brown eyes, a darker body and a much brighter blue saddle (the second segment); they fly between May and June. To be fair, if you see any medium-large dragonfly in the period from December to March it is likely to be a Vagrant Emperor. Therefore, keep your eyes open! Windmill Farm is one of the few places in the UK that you can see all three species of different Emperor dragonflies.
You are unlikely to confuse the larger (c. 8 cm) Emperor dragonfly with either of the above two species. Emperor males have a sky blue abdomen, and the females a green abdomen, both with a central dark line and an apple-green thorax.
Published: October 2019
Author: Dougy Wright
Photos: Dougy Wright