The Small Copper Butterfly lives in North America, Britain, and Ireland. They are orange with black spots and look like this:
The caterpillar is green and red.
Compare to other butterflies:
AKA Lycaena Phlaeas
They like to eat common sorrel and sheeps sorrel as host plants.
https://www.wildlifetrusts.org/wildlife-explorer/invertebrates/butterflies/small-copper