Although it is called the blue-tailed damselfly, this insect has a mainly black abdomen, with only a small amount of blue. A widespread damselfly, abdomen approximately 22-29mm in length. Males have a black abdomen with segment 8 coloured blue and a blue or green thorax. Females may have the same colours as the male or thorax colours may vary - some pinkish-brown, some purple and some green.