Peacock Butterfly Caterpillar Aglais (prev. Inachis) io
(European) Peacock butterfly caterpillars hatch in large communities, usually on nettles;
initially they construct a large silk net to protect themselves from predators.
When the young emerge from the silk web they are greyish with black spines, developing into black with white spots as they grow.
The caterpillar on the right of this group is most unusual, with a colourless head and white spines.
Peacock butterfly chrysalis
Links:
Peacock Butterfly