Common Blue

Polyommatus icarus

Nick Edge
Iain H Leach
Andrew Cooper
Matt Berry
Giles San Martin
Peter Eeles
Peter Eeles

What do they eat?

Caterpillars munch on:

  • Common Bird’s-foot Trefoil
  • Greater Bird’s-foot Trefoil
  • Black Medick
  • Common Restharrow
  • White Clover

Adults take nectar from a range of flowers including:

  • Bugle
  • Clover
  • Bird’s-foot Trefoil
  • Vetches
  • Wild Marjoram

Where does it spend the winter?

This butterfly spends the winters as a caterpillar. In the autumn, caterpillars crawl down the foodplant and find shelter under a leaf, or amongst nearby moss or leaf litter. They’ll stay there for five or six months, emerging in March the following year to carry on growing as a caterpillar.

Ideas to help Common Blue in your Wild Space



Flying Season

May - October

Life Cycle


May, June, July, August, September, October


May, June, July, August, September, October


January, February, March, April, May, June, July, August, September, October, November, December


April, May, July, August, September, October

UK Distribution

Want to learn


There is even more about this species on the main Butterfly Conservation website

Fun Facts
about the Common Blue

Like most of the Blue butterflies, caterpillars of the Common Blue produce a sugary substance called honeydew, which is attractive to ants. It allows the ants to feed on it, in exchange for protection from predators.