Southern damselfly  (Coenagrion mercuriale)

Males are sky-blue and black in colour, with blue eyes and two small eyespots. They can be distinguished from the males of similar species by the blue 'mercury mark' on the second segment of the abdomen, but detailed examination of the anal appendages is the only reliable method. Females do not possess these anal 'accessory genitalia' but have an ovipositor, which is not always easily visible (8). Females are generally green or blue and slightly lighter than males in colour, becoming brown as they age. They tend to have similar markings to males on the head and thorax but have darker abdomens. In both sexes the wings are clear with small black marks towards the tips (7).