Geometridae, Larentiinae - Wingspan: 32-36mm.

A distinctive species. Although generally found on calcerous terrain (hence the common name) in central and southern UK, it also occurs locally in the South-West wherever the wild Clematis known as "Traveller's Joy" grows. Although seen throughout Cornwall, records show a higher population to the west of the county.

The flight season in the UK is quoted as from early June to Late August, but in Cornwall, specimens can be seen as early as April, with a peak occurring in June / July.