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

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L. Watson and M. J. Dallwitz

Idaea Treitschke

Ania, Antesis, Arrhostia, Hyria, Ptychopoda, Sterrha.

Adults. Antennae of males with short, paired processes on either side of each joint, emitting fascicles of cilia (only in I. ochrata), or dentate (or sub-dentate), or simple (often filiform); simply-ciliate (nearly always), or fasciculate-ciliate (I. ochrata). Face smooth.

Wingspan (16–)18–30(–33) mm. Forewings relatively narrow-elongate to relatively broad. The outer margin of the forewing convexly curved (mostly), or sigmoid-curved; scalloped (in I. emarginata), or smooth. Forewings variously whitish, light to dark ochreous, whitish-, greyish- , reddish- or yellowish-ochreous, even purple; with a clear discal mark, or without a clear discal mark; with a distinct median band (this dark, e.g. in I. vulpinaria and sometimes in I. aversata), or without a median band. The outer margin of the hindwings rounded (nearly always), or rounded to angled; scalloped (in I. emarginata). Hindwings conspicuously patterned (via conspicuous wavy transverse lines), or plain (when the lines are faint); usually similar in colour to the forewings; with a clear discal mark, or without a clear discal mark; transversely lined (the first one often missing).

Vein 10 of the forewings arising out of vein 9. Hindwings exhibiting a tubular vein 5. Vein 5 of the hindwings arising from about 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 (usually), or separate.

Posterior tibiae of males without spurs (mostly), or 2-spurred (male I. ochrata; all females also with end spurs only).

British representation. 20 species (two adventive); South-east England, Central-southern England, South-west England, English Midlands, Northern England, Southern Scotland, Wales, and Ireland. Living adults found June to August. I. aversata (Riband Wave), I. biselata (Small Fan-footed Wave), I. contiguaria britanniae (Greening's Wave, Weaver's Wave or Capper’s Acidalia!) I. degeneraria (Portland Ribbon Wave), I. dilutaria (Silky Wave), I. dimidiata (Single-dotted Wave), I. emarginata (Small Scallop), I. fuscovenosa (Dark Cream Wave, Dwarf Cream Wave), I. humiliata (Isle of Wight Wave), I. inquinata (very occasionally recorded, mainly in London, associated with dried plant material in herbalists’ shops, I. laevigata (Strange Wave, adventive), I. muricata (Purple-bordered Gold), I. ochrata cantiata (Bright Wave), I. seriata (Small Dusty Wave), I. serpentata (Ochraceous Wave, of doubtful British status), I. straminata (Plain Wave), I. subsericeata (Satin Wave), I. sylvestraria (Dotted-bordered Cream Wave, Dotted Border Wave), I. trigeminata (Treble Brown Spot), I. rusticata atrosignaria (Least Carpet).

Subfamily. Sterrhinae.

Illustrations. • British Idaea (‘Waves’): Newman 1869. • Sterrhinae (‘Waves’): Kirby 44 (part). • Sterrhinae: Idaea degeneraria (Portland Ribbon Wave: B. Ent. 384). • Sterrhinae: Idaea degeneraria: B. Ent. 384, legend+text. • Sterrhinae: Idaea degeneraria: B. Ent. 384, text cont.. • Sterrhinae: Idaea muricata (Purple-bordered Gold: B. Ent. 523). • Idaea muricata: B. Ent. 523. legend+text. • Idaea muricata: B. Ent. 523. text cont.. • Idaea inquinata, I. ochrata, I serpentata.

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.’.