1668 Essex Emerald Thetidia smaragdaria
(Prout, 1935)Wingspan c. 35 mm.
Formerly resident in south-eastern England, occupying saltmarsh habitats around the Thames and other Essex estuaries and in northern Kent, this moth is now thought to be extinct in Britain. There have been no records of breeding since the early 1990s.
The larvae feed on sea wormwood (Seriphidium maritimum), and are very well camouflaged, attaching pieces of the foodplant to their bodies.
The adults fly in June and July in a single generation. The illustration shows the continental nominate subspecies rather than the British maritima.