Chalkhill blue

Chalkhill Blue butterfly

©Jim Higham

Chalkhill Blue butterfly

©Margaret Holland

Chalkhill blue

Scientific name: Polyommatus coridon
Unsurprisingly, the Chalkhill blue can be found on sunny, chalk grassland sites in southern England. Clouds of this beautiful blue butterfly may be seen fluttering around low-growing flowers.

Species information


Wingspan: 3.3-4.0cm

Conservation status

Protected in the UK under the Wildlife and Countryside Act, 1981.

When to see

July to September


As its common name suggests, the Chalkhill blue is found on chalk grasslands in southern England. It is on the wing from July to September. The blue males are most conspicuous as they fly around searching for the more secretive, brown females, and can sometimes be seen in huge numbers fluttering over flowers, or congregating on animal dung! The larval foodplant is Horseshoe vetch and the adults often feed on knapweeds and scabiouses.

How to identify

Apart from the very rare Large blue, the Chalkhill blue is our largest blue butterfly. Males are silvery-blue with a dark brown border and a white fringe on the wings. The females are brown with a white fringe to the wings and a blue dusting near the body. They look similar to Common blue females, but are larger and have chequered wing fringes. The orange wing spots are also less obvious in the female Chalkhill blue.


Found in southern England.

Did you know?

The caterpillars of the Chalkhill blue are always found with ants! The ants protect the caterpillars in return for a sugary substance that they produce.

How people can help

The Wildlife Trusts manage many grassland habitats sympathetically for the benefit of all kinds of butterflies, including the Chalkhill 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.