Holly Blue

Celastrina argiolus

Iain H Leach
Iain H Leach
Iain H Leach
Dean Morley
Gilles San Martin
Peter Eeles
Peter Eeles

Identification Tip

Holly Blues appear earlier in the year than other blue butterflies and are the only ones with blue on the underside of their wings, as well as the upper.

What do they eat?

Caterpillars munch on:

  • Holly
  • Ivy
  • Brambles
  • Spindle
  • Dogwoods

Adults take nectar from a range of flowers including:

  • Brambles
  • Buttercups
  • Forget-me-nots
  • Holly
  • Ivy

Where does it spend the winter?

This butterfly spends the winter as a chrysalis. Each autumn, caterpillars crawl down their plant and pupate, sometimes amongst roots or leaf litter, and sometimes on the food plant itself.



Flying Season

April - September

Life Cycle


April, May, June, July, August, September, October


April, May, June, July, August, September


May, June, July, August, September


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

UK Distribution

Want to learn


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

Fun Facts
about the Holly Blue

Holly Blue caterpillars change colour as they grow, from pale green to rich pink and eventually purple colour. Their head stays black, and is always tucked away inside their body unless they are feed, at which time it munches vigorously inside a flower bud whilst the rest of the body is perfectly still.