An endangered Red Data Book species, on shingle beaches, confined to Dungeness, Kent, protected under the UK Wildlife and Countryside Act, and a priority species under the UK Biodiversity Action Plan. Also an occasional migrant on the south coast of England from Dorset to Kent from 1902 onwards. In Hampshire and on the Isle of Wight there have been just two records, one at Bournemouth in July 1946, and a female at light at Binstead on the Island in June 2001. Wingspan 35-39 mm. The most likely confusion species is
Common Emerald Hemithea aestivaria, but Sussex Emerald has two projections on each hindwing. Larva feeds on Wild Carrot.