Choose which of the following your specimen most closely resembles then click on the image for more information.
Be aware that female and immature colouration is highly varaible.
Eyes are red (in male)
Body largely blue, eyes not red (in male)
Take care, these species are very similar.
There is an additional species which is currently only found in Ireland.
Cresecent shape and side-lines on S2
Body largely black, eyes not red