Celastrina argiolus
Caterpillars munch on:
Adults take nectar from a range of flowers including:
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.
There is even more about this species on the main Butterfly Conservation website
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.