Insects of Britain and Ireland: the genera of Lepidoptera-Geometridae

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L. Watson and M. J. Dallwitz

Thetidia Boisduval


Adults. Antennae of males bipectinate; apically simple. Face smooth.

Wingspan 33–35 mm. Forewings 1.5–1.7 times as long as wide. The outer margin of the forewing convexly curved to more or less straight. Forewings green; with a clear discal mark (this white). Hindwings plain; green; predominantly green when fresh; with a clear discal mark (white, proximally paler), or without a clear discal mark; transversely lined (with a white terminal line).

Vein 10 of the forewings arising out of vein 9. Hindwings exhibiting a tubular vein 5. Vein 5 of the hindwings arising from well above the middle of the transverse vein. Vein 8 of the hindwings shortly anastomosed basally with the upper margin of the cell, thence rapidly diverging. Hindwing veins 6 and 7 stalked.

Posterior tibiae of males 4-spurred.

Early stages. Larvae feeding on Artemisia, disguising themselves with attached fragments of the food-plant.

British representation. 1 species; South-east England. Living adults found in July. T. smaragdaria maritima (Essex Emerald, subspecies perhaps extinct).

Subfamily. Geometrinae.

Illustrations. • Geometrinae: Thetidia smaragdaria (Essex Emerald Moth: B. Ent. 300). • Geometrinae: Thetidia smaragdaria: B. Ent. 300, legend+text. • Geometrinae: Thetidia smaragdaria: B. Ent. 300, text cont.. • Geometrinae: Newman (1869).

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Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of Lepidoptera-Geometridae. Version: 8th June 2016.’.