Sussex emerald moth (Thalera fimbrialis)

KingdomAnimalia
PhylumArthropoda
ClassInsecta
OrderLepidoptera
FamilyGeometridae
GenusThalera (1)
SizeWingspan: 35- 39 mm (1)

Afforded full protection under the Wildlife and Countryside Act 1981 (2).

This moth was given the common name 'Sussex Emerald' because it was first identified in Britain at Beachy Head in Sussex in 1902. Adults are an attractive pale green colour with reddish flecks at the edges of the wings. The forewings are crossed by two wavy white lines, and the hindwings have just one cross-line (1). The striking caterpillars are yellow-green in colour with a red line along the back, which may occur as a row of dots. Two spikes that are tipped with red protrude out from the body and reach over the head, which is drawn into two points (3).

At present the Sussex Emerald is known from just one site, Dungeness; the largest stretch of shingle in Europe. It is now extinct as a resident breeding species at the Crumbles near Eastborne in Sussex. There are single records of strays or migrants from Dorset, Swanage, Bournemouth, Hampshire, Essex, Beachy Head, and Northiam in Sussex. This species is known throughout central Europe, and the range extends east to central Asia (1).

At present, this moth is only recorded on one shingle beach in Britain (1).

The Sussex Emerald is a single-brooded species; adults are active in July and early August and fly just after nightfall (1). The caterpillars are found towards the end of August through to the June of the following year, with a period of hibernation in winter (1). They are known to feed on yarrow, gorse and a range of other low-growing plants (1), but the majority are found on wild carrot (4).

The species is a recent colonist in the UK (5), where it is at the north-western extreme of its range (6).

Dungeness is a National Nature Reserve (NNR), a Special Area of Conservation (SAC), a Special Protection Area (SPA) and a Site of Special Scientific Interest (SSSI). Very little active management is needed at the site to preserve the habitat for native flora and fauna (7). The Sussex Emerald moth is not a UK Biodiversity Action Plan priority species.

Further reading on moths:
Leverton, R. (2001) Enjoying Moths. Poyser, London.
Skinner, B. (1984) Moths of the British Isles. Penguin Books, Harmondsworth

Information authenticated by David Walker.

  1. Skinner, B. (1984) Moths of the British Isles. Penguin Books, Harmondsworth.
  2. JNCC (12/2001): http://www.jncc.gov.uk/species/protect/animals.htm
  3. Carter, D.J. and Hargreaves, B. (1986) A field guide to caterpillars of butterflies and moths. William Collins and Sons, London.
  4. Walker, D (2002) Pers. comm.
  5. South, R. (1961) Moths of the British Isles. Frederick Warne and Co. Ltd, London.
  6. Pers. observation from image.
  7. British Energy (12/2001): http://www.british-energy.com/environment/annual00_she/site_reports/mn_dungeness_land.shtml