Cossonus linearis (Fabricius, 1775)

A locally common species throughout Central and Southern Europe, also known from Gibraltar and many of the Mediterranean islands but absent from North Africa, to the north it extends sporadically to the UK, Denmark and the Southern Baltic countries, it is known from the extreme south of Sweden but is otherwise absent from Fennoscandia, and to the east it extends through Asia Minor, Russia and Kazakhstan into Mongolia and Western Siberia. In the UK it is very local and generally scarce although it seems to be expanding its range, at present it is widespread across East Anglia and there are scattered records from the South East and the Midlands but a recent record from the Cornish coast would suggest a much wider occurrence. Typical habitats are humid deciduous woodland and parkland with plenty of trees in various stages of decay but they may occur in carr and on individual trees in suitably damp grassland and moorland etc. or on wetland margins. Adults occur year-round, peaking in abundance during May and June; they are active from March until August or September and are strictly nocturnal, usually occurring on damaged trunks or fallen timber and often in numbers. A wide variety of broadleaf trees have been recorded hosting the species and they sometimes, though rarely, occur on conifers in mixed woodland, but by far the commonest hosts are various poplars (Populus L.) and willows (Salix L.). Mating occurs in the summer and larvae develop among damp decaying wood in trunks and stumps, it is likely they overwinter as teneral adults have been recorded in June. Nocturnal searching is probably the best way to find adults as they feed on decaying wood and often crawl (and they will run quickly and readily enter crevices when disturbed) on the surface of logs etc., by day they hide under bark and in crevices and occasionally, especially during May and June, occur in groups of fifty or more specimens.