Silvery blue
Its caterpillars secrete substances that ants feed on, and in return the ants guard them from parasitic wasps.
| Where | Meadows, open woods and roadsides |
|---|---|
| Size | 18 to 32 mm wingspan |
| When | March to July |
The Silvery blue is a small butterfly with a wingspan of about 18 to 32 mm. Males are iridescent silvery blue with narrow dark borders, while females are duller blue to brown with wider borders, and both show a single row of white-ringed black spots on the pale underside.
Caterpillars feed on the flowers, seedpods and young leaves of lupine, milkvetch and other pea-family plants, and are tended by ants that feed on their secretions in exchange for protection. A single generation flies each spring, timed to the flowering of its host plants.
Traits
Habitat
Grassland
Colour
Blue, Grey, White
Active
Day
To people
Harmless to people; caterpillars depend on tending ants.
Activity through the year
Often confused with
Has a thin tail and small orange spot near the base of each hindwing, features the Silvery blue lacks.
Questions
Is the Silvery blue dangerous to people?
Harmless to people; caterpillars depend on tending ants.
When can you see the Silvery blue?
The Silvery blue can be seen from March to July, by day.
Plate retouched from a photo by Bernie Paquette, CC BY 4.0, iNaturalist Licence
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Butterflies and moths›Blues and coppers›Glaucopsyche
Last updated 2026-09-27. Every entry is checked against published sources.