This is the Wall Brown, living up to its name resting on a bit of dry-stone wall that stops our ramp from collapsing onto the steps. Look how its white dots seem to pop out of the picture!
I wanted to know why so many butterflies have vibrant dots. There are a few hypotheses about this. The large ‘eyespots’ like those of the Peacock butterfly will fool predators into thinking that the eyes are of something much larger and more dangerous. At the very least some are put off or confused by a jazzy wing pattern. Smaller bright dots, like those on the Wall Brown serve as targets to divert predators from fatally wounding the butterfly by going for its head or body.
The Wall Brown is found in grassland and the caterpillars are found on various grasses including Cocksfoot grass, which we have here.
The Meadow Brown is also found in grassland and the caterpillars would have been enjoying our Cocksfoot grass. It is quite common, and we have been chasing this one for a couple of weeks trying to get a good photograph. At last it settled on the buddleia which overhangs our ramp.