The Essex emerald (''Thetidia smaragdaria'') is a

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

of the family Geometridae. The species was first described by

Johan Christian Fabricius Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is cons ...

in 1787 as ''Phalaena smaragdaria''. It is distributed throughout the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

region with records from many European countries. The British subspecies ''Thetidia smaragdaria maritima'' was last seen in 1991 in

Kent Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...

and is now presumed extinct. In 2004 the moth was first recorded from

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

. The

wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan of ...

is 27–35 mm. There is one generation per year with adults on wing from mid-June to mid-July. The larvae feed on ''

Artemisia maritima ''Artemisia maritima'' is a European species of wormwood known as sea wormwood and old woman. It is native to France, the United Kingdom, Italy, Belgium, Germany, Denmark, Sweden, Bulgaria and Russia. In its many variations of form it has an e ...

'' and ''

Achillea millefolium ''Achillea millefolium'', commonly known as yarrow () or common yarrow, is a flowering plant in the family Asteraceae. Other common names include old man's pepper, devil's nettle, sanguinary, milfoil, soldier's woundwort, and thousand seal. The ...

''. Larvae can be found from July to June the following year. It overwinters in the larval stage.

Subspecies

*''Thetidia smaragdaria smaragdaria'' *''Thetidia smaragdaria gigantea'' Milliere, 1874 *''Thetidia smaragdaria maritima'' Prout, 1935 *''Thetidia smaragdaria volgaria'' Guenee, 1858

References

External links

Essex emerald at ''UKMoths''''Fauna Europaea''''Lepiforum e.V.''
Geometrinae Palearctic Lepidoptera Taxa named by Johan Christian Fabricius Moths described in 1787 {{Geometrinae-stub