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

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L. Watson and M. J. Dallwitz

Schoenobius Duponchel

Adults. Face without a conical hairy prominence. Proboscis atrophied. Labial palps relatively very long.

Wingspan 25–30 mm (male), or 41–46 mm (female). The adults conspicuously sexually dimorphic. Forewings in the male, rather broad with bunt apex, light ochreous-fuscous, sometimes tinted reddish or heavily irrorated blackish, usually with two small dark discal spots and often other more or less conspicuous dark dots along the major veins and subterminally; in the female relatively much narrower with oblique termen and pointd apex, brown-ochreous, exhibiting blackish discal, other scattered spots and a blackish subapical streak, or almost unmarked, rarely anteriorly heavily suffused blackish from base to apex. The fringe not glistening-metallic. Forewing apices fairly rounded; termen somewhat sinuate (in the female), or non-sinuate. Ground colour of the forewings ochreous, or brown, or brown to grey (fuscous). Forewings fairly inconspicuously patterned (darkly streaked and dotted), or plain. The patterning simple; restricted to longitudinal streaking, or consisting of dark dots. Forewings without a median line; not transversely dark-lined towards the termen; without a strong white median streak; without conspicuous white marks at or near the apex. Hindwings white to whitish, or ochreous whitish; plain, or with a subterminal dark line and fuscous termen; in the male glossy, white, darkened to pale grey subterminally, with a postmedian band of short dark streaks and a terminal line of dots, white-fringed; in the female unmarked, pure white or tending somewhat ochreous towards the apex, white-fringed.

Distribution and habitats. England (only south of Yorkshire, local). Occurring in coastal locations (mainly), or inland. In wet places. British species: S. gigantella. Adults abroad July.

Larvae. Larvae feeding on monocots; Poaceae (in the stems of Pragmites and Glyceria maxima. Moves from culm to culm on a raft constructed of stem material, and pupates upright within a stem below a previously prepared exit hole). Confined to large reed beds.

Subfamily. Schoenobiinae.

General comments. The adults seem scarcely distinguishable morphologically from those of Donacaula, except they tend to be larger.

Illustrations. • Schoenobius gigantella, with Donacaula, Chilo, Calamotropha and Pyraustinae: Leech, 1886. • Schoenobius gigantella, with Donacaula: Barrett. • Donacaula forficella and Schoenobius gigantella, with mainland-European S. consortella and Scirpophaga praelatella: Hübner (1796).

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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.’.