The Sussex Emerald (Thalera fimbrialis) moth is a very rare beast in the UK
With breeding traditionally restricted to the disturbed shingle habitats at Dungeness in Kent (though it has colonised two other sites further east in the county in recent years).
Adults are active between July and early August and the eggs are laid (and the larvae usually feed) on Wild Carrot, though both Common Ragwort and Hoary Ragwort (and more rarely Yarrow and Gorse) are utilised as a secondary food-plants in the UK.
As its name suggests, this species was first found in the UK in Sussex and there were several records around the Beachy Head / Eastbourne area prior to the 1950s. Since then it has occurred only as an occasional immigrant and at Rye Harbour previous to 2019 there had only been two records, with singles on two dates in July 2010.