Otiorhynchus tenebricosus (Herbst, 1784)

More generally known as O. clavipes (Bonsdorff, 1785), this is a very local and generally scarce species throughout central and southern Europe from France to Ukraine and western Russia and north to the UK and Denmark, throughout much of this range it is more prolific in deciduous and mixed mountain forest areas but it now occurs more generally as it is widely polyphagous and the subterranean larvae are readily transported with horticultural products. Here it is very local across south and central England and generally rare further north, across Wales and in Northern Ireland, it was formerly present as far north as Southern Scotland but it seems to have declined over recent decades. Typical habitats are mostly in dry chalky districts, often in upland areas on grassland or at the roots of various trees and shrubs and it is also an occasional pest of cultivated fruits. Adults appear from late April or May and again from mid-June until August, their appearance depending upon when pupation occurred; they overwinter either as young larvae which will develop through the spring and pupate in early summer, or as fully-grown larvae which will pupate early in the spring, pupae have also been known to overwinter and produce adults earlier in the year. They are nocturnal, feeding on the foliage of a wide range of herbaceous and woody plants by night and hiding under stones or among foliage by day, reproduction is both parthenogenetic as well as sexual, mating occurs after a period of feeding and pairs may be found over a long season from May or June. Females are fecund and each may produce up to 300 eggs which they scatter in batches onto the ground beneath likely host plants, larvae emerge after about 3 weeks and enter the ground to feed on plant roots, they pass through three instars and develop rapidly although even those from early summer, except for the few that pupate late in the year, will go on to overwinter. As a pest they rarely cause serious damage, adults feed on developing foliage and fruit buds and later in the season they may attack the stems of raspberry canes etc, the damage is usually slight but where the species becomes established the larvae may cause more serious damage by attacking the roots of soft fruits. Adults may be sampled by sweeping grass and low foliage around trees and shrubs at night; on the continent, and especially at higher altitudes, they are often more prolific in woodland where the adults feed on developing shoots of both conifers and broadleaf trees and larvae develop among the roots, but more generally the species feeds on a very wide range of plants; when we found them in the Chilterns they were just as numerous on hazel and hawthorne (etc) in hedgerows and copses as they were among long dry grass on open hillsides and so sweeping any vegetation on chalky soil at night is probably worthwhile. Adults can be seen by torchlight on foliage and they also sit on fence posts etc for long periods but they drop to the ground at the slightest disturbance and can be very difficult to find.