Widespread but very localised. The smallest of the Irish damselflies. A delicate species which stays close to water. Adults have been recorded from mid May to September. Found in shallow seepages, often at altitude, either in natural situations such as flushes and springs or in artificial habitats such as quarries. It can also be found on the margins of large limestone lakes. Also has a pronounced tendency to wander and individuals can turn up well away from breeding sites, so allowing it to colonise new sites. Colonies are often short-lived, as the species is prone to disappear when seepages become well-vegetated.
Males of this species are similar to males of the commoner Blue-tailed Damselfly Ischnura elegans and positive identification requires examination in the hand. In males of the Scarce Blue-tail the blue on the tail covers all of segment 9 and the posterior part of segment 8 whereas in the Blue-tail it is confined to segment 8.