Essex Emerald

  • Essex Emerald
    Essex Emerald

Scientific name: Thetidia smaragdaria

Mid-June to mid-July. Now presumed extinct, previously only recorded on the coastlines of Essex and Kent.

A golden leading edge to the forewing and white central spot are diagnostic. The wing fringes are plain.

The adults fly at night and are attracted to light. The caterpillars can be found from August to late the following May, overwintering low down on the foodplant. They camouflage themselves by attaching parts of the foodplant to their bodies.

Size and Family

  • Family – Emeralds (Geometridae)
  • Medium Sized
  • Wingspan Range – 28-34mm

Conservation Status

  • UK BAP: Not Listed
  • Previously rare (Red Data Book) now presumed extinct

Caterpillar Food Plants

Sea Wormwood (Seriphidium maritimum)


Upper saltmarsh zones above the tideline


  • Countries – England and Wales
  • Local, presumed extinct. Only ever recorded on the coast in Essex and Kent. The last records dated from in the early 1990s.