Insects of Britain and Ireland: the genera of grass moths (Pyralidae-Crambinae and Schoenobiinae)

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L. Watson and M. J. Dallwitz

Platytes Guenée

Adults. Face without a conical hairy prominence. Proboscis functional.

Wingspan 12–15 mm (P. cerussella), or 18–22 mm (P. alpinella). The adults conspicuously sexually dimorphic (in P. cerussella), or not very sexually dimorphic. Forewings in P. alpinella, whitish irrorated cuscous along the dorsum and with a broad fuscous costal band extending into the apical projection, and dorsal to this a fine white median longitudinal stripe most clearly defined over the basal 2/3; a fine, faint, angulated oblique median crossline, and a brown, white-edged oblique subterminal line angled towards costa and tornus, the fringe whitish and shining with cilia of unequal lengths. In male P. cerussella ochreous to ferrugineous or fuscous-brown, in the female whitish with ferrugineous irroration towards the apex; oblique median and subterminal lines and black dots at the tornus more apparent in the male than in the female; fringe in the male grey and darker than the ground color, with a dark line near the base, glistening-metallic, and in the female whitish with a broken, ferrugineous basal line. The fringe glistening-metallic (at least towards the middle of the forewings), or not glistening-metallic. Termen sinuate (very much so in P. alpinella, resulting in a conspicuous apical projection), or non-sinuate (slightly convex, in P. cerussella). Ground colour of the forewings whitish, or brown. Forewings plain (P. cerussella), or inconspicuously patterned (P. alpinella). The patterning in P. alpinella complex; mainly restricted to longitudinal streaking. Forewings ostensibly without a median line, or with a median line (this faint, oblique); transversely dark-lined towards the termen; the subterminal lines conspicuously white-edged (in P. alpina), or not white-edged; with a strong white median streak (only in P.alpina), or without a strong white median streak; the median streak without a cross-bar; without conspicuous white marks at or near the apex. Forewing vein 7 free. Hindwings pale fuscous, or pale grey, or dark grey; plain; in P. alpinella grey, darkening away from the base, with a fine dark terminal line and a contrasting, pale fringe. In male P. cerussella dark fuscous with a fine, broken ferrugineous terminal line and whitish fringe, in the female much paler, with a white fringe.

Distribution and habitats. England and Ireland (England south of Yorkshire, with P. alpinella also recorded from Co. Cork). Occurring in coastal locations (mainly inhabiting coastal dunes and shingle beaches), or inland. Mesophytic habitats to dry places. British species: P. alpinella, P. cerussella (the adults very different in appearance). Adults abroad June to August.

Larvae. Larvae feeding on mosses (P. alpinella), or monocots; Poaceae and Cyperaceae (P. cerusella).

Subfamily. Crambinae.

General comments. On mosses (P. alpinella), or grasses and sedges (P. cerussella).

Illustrations. • Platytes alpinella and P. cerussella, with species of Catoptria and Crambus: Leech, 1886. • Platytes alpinella and P. cerussella, with Euchromius: Barrett. • P. alpinella, with Calamotropha, Haimbachia, and Talis: Hübner (1797–1824).

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Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the genera of grass moths (Pyralidae-Crambinae and Schoenobiinae). Version: 8th June 2016.’.