Best time to see: mid Jul to late Aug

Key facts

A butterfly that spends most of its time perched at the top of oak trees

Habitat: anywhere with mature oaks, but usually within woods

Probably in every wood in Wales and southern England with a number of oak trees

Recognition

Inky black upperwings turning deep purple in the sun; silver-grey underside with a white streak and an orange eye

Most of the time adults perch on the canopy with wings closed; a few can often be seen tumbling above the tree

Live in separate colonies that vary considerably in size from year to year

Lifecycle

Pinhead-sized grey eggs laid singly at the base of flower buds or on twigs in late summer

Brown, woodlouse-shaped caterpillars hatch in spring and enter bursting oak buds to feed, later feeding on leaves

In June they drop to the ground and pupate, the chrysalis sometimes entering ant nests; adults emerge in late summer