Dark cerulean
Male Dark Ceruleans flash a deep metallic blue that vanishes the instant they close their wings, since the closed underside shows only pale wavy lines.
| Where | Lowland forest edges and flowering scrub |
|---|---|
| Size | 11 to 16 mm forewing length |
| When | May to January |
The Dark cerulean is a small blue butterfly. Males show a deep, glossy metallic blue upperside with a black outer border, while females are paler blue with more black along the margins. The underside of both sexes is pale grey brown, crossed by a continuous wavy white line.
Caterpillars feed inside the flower buds and young seed pods of pea family vines, and adults visit flowers at forest edges through most of the year across their range, with several overlapping generations and no long break in activity.
Traits
Habitat
Woodland
Colour
Blue, Metallic, Black
Active
Day
To people
Visits garden and forest edge flowers; harmless to people.
Activity through the year
Often confused with
Metallic cerulean shows a paler, greyer blue upperside, and its underside markings form a broken, dotted line rather than the Dark cerulean's continuous wavy white line.
Questions
Is the Dark cerulean dangerous to people?
Visits garden and forest edge flowers; harmless to people.
When can you see the Dark cerulean?
The Dark cerulean can be seen from May to January, by day.
Plate retouched from a museum specimen photo by Swiss Natural History Collections - SwissNatColl, CC BY 4.0, GBIF Licence
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Butterflies and moths›Blues and coppers›Jamides
Last updated 2026-09-27. Every entry is checked against published sources.