Caterpillars munch on grasses including:
Adults feed on honeydew (made by aphids) in the treetops and are rarely seen feeding on flowers, except early and late in the year when aphid activity is low.
Speckled Woods spend the winter either as a caterpillar or a chrysalis. Hibernating caterpillars fix themselves to a grass stem with silk but may wake up to feed if the weather is mild enough.
Chrysalises are either amongst the grass or occasionally on a fence or a plant pot.
There is even more about this species on the main Butterfly Conservation website
If a female is approached by a male that she doesn’t want to mate with, she "plays dead" until he loses interest and flies away.