The males of this species are light blue to blue with black markings. They can be confused with the males of C. puella from which they can be distinguished by a general darker colouration, the larger extension of the black markings on the abdomen. The pattern makes the shape af a Y instead of a U on S2 and the antehumeral stripes often being split and thereby resembling an exclamation mark.
Sometimes the antehumeral stripes are complete but have a narrower neck towards the rear part ot the thorax. Sometimes the marking on S2 is not connected to the hind margin, making it look like C. puella. But any male with both broken antehumeral stripes and a good Y-shape on S2 should, with certainty, be a C. pulchellum.
The females have two colour forms, blue or green, like C. puella. Their identification is difficult and can only be done with certainty by looking at the shape and hind margin of the pronotum, that being dented in three points, form three lobes.
To find plenty of this species, look at edge zones, like sunny wind-protected glades and like. At really good spots you can find thousands of individuals.
Coenagrion pulchellum is widespread in central Europe but missing from most of the Iberian Peninsula and northern parts of Fennoscandia. It is rare in parts of mainland Italy and absent from Sicily. The species is reasonably common on Corsica but absent on Sardinia. In the Balkan Peninsula it becomes scarcer towards the south, but reaches the southern Peloponnese in Greece. In the Iberian Peninsula the species is rare and scattered in northern Spain. Only one recorded observation is made in Portugal but more small overlooked populations might exist in both Spain and Portugal.
Coenagrion pulchellum is found in standing waters and slow-flowing sections of rivers. Habitats are largely unshaded oligotrophic, mesotrophic or eutrophic and nearly always have a well-developed bank-side and aquatic vegetation. Favoured habitats include lakes, ponds, fens, peat bogs, oxbows, ditches and canals. The species is generally absent from fast-flowing waters. C. pulchellum is mainly found in lowlands but breeds up to 1 500 m in southern Europe.