Sometimes in Nature it’s easy to overlook things. We have three clear-winged Emerald Damselflies in the UK. Two of them, the common Emerald Damselfly and the much rarer Scarce Emerald Damselfly, are not easy to tell apart – especially the males. In fact it was thought until the 1970’s that the Scarce ED was extinct here in the UK. In reality it had probably been overlooked. Here in Norfolk both species can appear together at the same sites.
The key to telling the males apart is by a close examination of their inferior anal appendages. I know. Sounds disgusting doesn’t it. However, with a good close focus pair of binoculars the tail end of these little odonata can, with practice, give their identification away … without any use of rubber gloves! :0) Looking at the tail end there are a pair of superior anal appendages on the outside and inferior anal appendages within them. On Scarce ED those inferior anal appendages are club shaped and on ED they are straight.
I promise that’s the last time you’ll hear the phrase ‘anal appendages’ today!
Letter From Norfolk 