Small Blue butterfly

┬ęChris Lawrence

Small blue

Scientific name: Cupido minimus
The small blue's name is a little misleading: it is our smallest butterfly, but only shows a dusting of blue on brown wings. It is scarce, occurring on chalk grassland, mostly in southern England.

Species information


Wingspan: 1.8-2.7cm

Conservation status

Protected in the UK under the Wildlife and Countryside Act, 1981. Priority Species under the UK Post-2010 Biodiversity Framework.

When to see

May to August


The small blue is the smallest of all the UK's butterflies. Adults are on the wing from May to August and can be seen feeding on common bird's-foot-trefoil or horseshoe vetch on chalk grassland, but only where kidney vetch also grows - the sole foodplant of the caterpillars. Males set up territories in sheltered places and the females lay their eggs on the kidney vetch; the emerging caterpillars feed on the flowerheads.

How to identify

Despite its name, the male small blue only has a small dusting of blue near to its body, otherwise it is a brown butterfly with pale, silver-grey underwings. The female is similar, but without the blue markings on the upperwings.


Mostly found in southern England, but also in parts of Scotland and Wales.

Did you know?

The small blue tends to live in small colonies of up to 30 individuals. Both sexes can be found in communal roosts, facing head down in the grass.

How people can help

The Wildlife Trusts manage many grassland habitats sympathetically for the benefit of all kinds of butterflies, including the small blue. Careful grazing with traditional breeds, hay-cutting at the right time and scrub clearance are just some of the ways grasslands are kept in good condition - supporting invertebrates and, in turn, the larger animals that prey on them. By volunteering for your local Trust you can help too, and you'll make new friends and learn new skills along the way.