Blue-tailed Damselfly Ischnura elegans
A common species found in a wide variety of habitats (from late May until September), including brackish waters.
The male has a blackish abdomen with a blue segment 8 on the abdomen. The lower thorax is blue as are the eyes.
Females have several colour forms (at least 5), violacea, infuscans, rufescens, infuscans-obsoleta and typica which is the same as the male. The only difference between the sexes in this form is the spur under segment 9 of the female's abdomen, not an obvious feature!
Although this seems complicated, basically a blackish abdomen with a ‘coloured’ (usually blue) eighth segment to the abdomen denotes a Blue-tailed Damselfly.
The Scarce Blue-tailed Damselfly Ischnura pumilio is a rare damselfly and easily overlooked, but has been seen in recent years in Norfolk.