As its name suggests, this strinking green coloured species was first found in the UK in Sussex and there were several records around the Beachy Head and Eastbourne area prior to the 1950s. Since then it has occurred only as an occasional immigrant.
Now thanks to conservation work at Rye Harbour Nature Reserve, in the east of the county, it is becoming established again.
Before the work at Rye Harbour, breeding traditionally restricted to the disturbed shingle habitats at Dungeness in Kent.
Initially, management to encourage this species at Rye Harbour began with the removal of large swathes of Red Valerian which had come to dominate, followed by the by collection and spreading the seeds of Wild Carrot, one of Sussex Emerald’s main food plants, at various points around the reserve, but particularly within the fenced rabbit exclosures on the Beach Reserve, the habitat most similar to that found at its traditional breeding sites in Kent.
This effort appears to have paid off and from 2019 adult moths became relatively abundant in the moth trap, with a total of 22 trapped in 2019 and 15 in 2020. There was a strong suspicion that this species was breeding at Rye Harbour. A search for larvae in May 2020 was unsuccessful, but a return visit by moth expert Sean Clancy and Rebecca Levey of ‘Kent’s Magnificent Moths’ on June 10 found two well-grown larvae on Wild Carrot in the grassy area just to the west of the temporary visitor centre, the first ever found in Sussex.
Adult Sussex Emeralds are active between July and early August and the eggs are laid, with the larvae usually feeding on Wild Carrot, though both Common Ragwort and Hoary Ragwort and more rarely Yarrow and Gorse are utilised as a secondary food-plants.