Insects of Britain and Ireland: the genera of Lepidoptera-Geometridae
Adults. Antennae of males bipectinate (P. didymata), or simple (mostly). Face rough.
Wingspan 18–30 mm. The outer margin of the forewing slightly sigmoid-curved, or convexly curved. Forewings not predominantly green, yellow, or black; whitish, ochreous-greyish, ochreous-brown, fuscous, usually striated darker; predominantly whitish, or pale ochreous, or brown, or pale fuscous, or fuscous, or pale grey; with a clear discal mark, or without a clear discal mark; with a distinct median band (this dark to very dark, or partial only and represented by the whitish rivulet), or without a median band (or poorly distinguished); often with a transverse post-median rivulet (i.e., with a narrow, wavy, white post-median median transverse band divided by a correspondingly wavy londitudinal dark line), or without a post-median rivulet; without an oblique red stripe. The outer margin of the hindwings smooth. Hindwings plain (though often faintly darker- or lighter-banded); whitish, grey or pale fuscous; not predominantly green, yellow, or black; with a clear discal mark, or without a clear discal mark; transversely lined to without transverse lines.
Vein 10 of the forewings arising independently of 9; arising independently, anastomosing with 11 and 9 to form a double areole. Hindwings exhibiting a tubular vein 5. Vein 5 of the hindwings arising from about the middle of the transverse vein, or arising from below the middle of the transverse vein (?). Vein 8 of the hindwings approximated to or anastomosed with the upper margin of the cell to the middle or beyond. Hindwing veins 6 and 7 stalked.
Posterior tibiae of males 4-spurred.
Early stages. Larvae feeding on diverse Dicot herbs, especially Scophulariaceae.
British representation. 12 species; South-east England, Central-southern England, South-west England, English Midlands, Northern England, Southern Scotland, Northern Scotland, Wales, and Ireland. Living adults found May to August (sometimes double brooded). P. affinitata (The Rivulet), P. albulata (Grass Rivulet), P. alchemillata (Common Carpet), P. bifaciata (Haworth's Carpet, Barred Rivulet), P. blandiata (Pretty Pinion), P. didymata (Twin-spot Carpet), P. flavofasciata (Sandy Carpet), P. minorata (Heath Rivulet), P. sagittata (Marsh Carpet), P. taeniata (Barred Carpet).
Illustrations. • 10 Perizoma species (Rivulets, etc.), with Epirrita, Operophtera: Newman 1869. • Larentiinae (‘Rivulets’, ‘Carpets’, ‘Pugs’, etc.): Kirby 51.
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
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. delta-intkey.com’.