Pseudorchestes pratensis (Germar, 1821)

This is a mostly Western Palaearctic species that is also known from the Oriental region; it is widespread in Europe from France to Italy and Greece in the south, although it is generally absent from the Mediterranean islands and North Africa, and extends north into the UK, Germany, Poland and Estonia, it is generally absent from Asia Minor but has been recorded from Georgia and sporadically further east into Western Siberia. In the UK it is a very local species of South East and Central England and South Wales, extending north as far as Leicester and Wrexham. The species is unusual among the tribe because it is associated with herbaceous vegetation rather than trees and shrubs; all seventeen or so European members of the genus are associated with various Asteraceae and the present species, which is the only one to extend into the UK, occurs Common Knapweed (Centaurea nigra L.) although it is also recorded from Brown Knapweed (C. jacea L.) and Greater Knapweed (C. scabiosa L.) on the continent. Typical UK habitats are open grassland and dry areas on wetland margins, especially on basic soils, while on the continent it occurs more generally; in damp grassland and pasture, scrub and open deciduous woodland. Adults are present year-round; they overwinter among tussocks or litter etc. and are active from March or April until October, peaking in abundance from May to July, the breeding cycle is poorly understood in the UK, but in parts of Northern Europe there may be two generations each year with fresh adults appearing in May and June, and again in July and August. Mating occurs early in the season and females lay single eggs on the margins of host leaves. Larvae are leaf-miners; they enter the leaf and form a shallow blotch mine with the frass deposited along the centre, this blotch may eventually expand to include most of the leaf before the fully-grown larva pupates among the frass. Females lay between 10 and 20 eggs and larval development takes between 20 and 24 days. Adults can be found by the usual methods of sweeping foliage during spring and summer or by taking suitable winter samples for extraction.