Tomicus piniperda (Linnaeus, 1758)

Native to the Palaearctic region this generally common species is one of the most destructive shoot-feeding bark beetles of northern conifer plantations, it occurs throughout Europe north to Scandinavia and the UK and east through Siberia to China, Korea and Japan, it also occurs in North Africa and has become established and is spreading in the USA since being first discovered in 1992 in a Christmas tree plantation in Ohio. In the UK it is common throughout England and Wales and more sporadic in Scotland, occurring mostly in the northern Highlands. The primary host is Scots pine, Pinus sylvestris L., but other species of pine are also attacked as well as, more rarely, species of Picea, Larix and Abies. In warmer regions there may be two generations each year but in northern temperate areas, including the UK, it is univoltine with adults occurring virtually year-round; they overwinter at the base of trees or in hollows in twigs and branches and become active very early in the year, generally from February or March when they may disperse by flight to find suitable hosts; flight occurs when the daily mean temperature reaches 7 or 8°C and they may fly several kilometres, they prefer to colonize fallen timber and freshly cut stumps but will also attack stressed living trees and usually attack wood exposed to the sun, upon finding suitable host material they bore into bark at the base of trunks etc. to construct brood galleries. The galleries are generally straight and vertical and vary between 10 and 25cm in length, eggs are laid at regular intervals along the gallery and adults then move out of the bark and into the crowns of trees for ‘regeneration feeding’, they then move back down and construct one or several further galleries and then they die off. Larvae emerge after a few days and begin feeding, producing meandering galleries between 2.5 and 10cm long perpendicular to the brood gallery, they develop rapidly and are fully grown by late May or June when they pupate at the end of their feeding galleries. New generation adults bore through the bark and migrate to growing shoots high up in trees, here they do the most severe damage, boring feeding galleries up to 10cm long among the pith and very often destroying the growing tip completely, and severe infestations, especially when coupled with stem damage produced by the larvae or the introduction of fungal pathogens etc. may be lethal. This generation remains active through the summer and will go on to overwinter. This is considered to be the most serious pest of commercially grown Pines in Europe, it usually attacks stressed, weakened or dying trees but large populations build up readily and healthy trees are then attacked and killed; in China it has caused great economic loss by killing large numbers of healthy Pinus yunnanensis L. and in the United States it is a severe pest of, among others, Loblolly pine, P. taeda L. which is the primary source of Christmas trees. Infestations on pine may be recognized by yellowing of branches, dieback or terminal shoots and small branches displaying multiple exit holes some 2-3mm in diameter littering the ground around the tree. Adults are readily obtained by searching under bark etc. early in the year or by using alcohol or flight-interception traps.