The male variable damselfly has a distinctive wine glass–shaped marking on its abdomen. Both males and females are blue, although the males appear darker due to their more extensive black markings. They have long, slender abdomens, measuring 25 to 30 millimetres. The total body length is 34 to 38 millimetres, and the hind wings are 16 to 21 millimetres long.
Variable damselflies are widespread throughout Europe. They live around still or slow-moving waters with rich aquatic vegetation and can be seen in flight between May and August.
Females lay their eggs under water on the lower parts of aquatic plants in still or slow-moving water bodies. The larvae are semi-transparent, making them hard to spot among vegetation.