The Sussex Emerald moth is one of Britain's rarest moths. It is confined to a single site in the South of England. There it mainly uses wild carrot as a foodplant but ragwort is sometimes used as a secondary food. It flies in July and August.

It is a good illustration of the fact that an insect may be rare even though its foodplant is common Wild Carrot like Ragwort is not a scarce plant yet this creature is extremely scarce and vulnerable. There are many ecological factors which affect the occurrence of any given species. Species may be rare even though their habitat seems common.