|Tomicus piniperda (Linnaeus, 1758)|
This specimen is not typical in colouration and is almost certainly teneral
Occurs throughout mainland UK and stated by Bevan to be
'among the commonest scolytids in Britain'. Host plants are various conifers eg scotch pine (Pinus sylvestris),
spruce (Abies spp.) and larch (Larix spp.) and the species has been considered as the most serious pest of
pines in Europe; its former reputation as a serious threat to pines in the UK has not been entirely fulfilled. Although
it may infect and kill healthy specimens it especially attacks weakened, drought stressed, defoliated or dying trees.
Adults attack the trunks and growing shoots of trees; the most severe damage is caused by shoot tip feeding and this may
destroy the tree entirely or, at the very least, cause various deformities. Hanson (1937) states ' This destruction of
the growing point causes various forms of malformation... and results in great reduction of the value of the crop....the
injuries caused are of a permanent character and the record of the attack is indelibly stamped on the tree'. Adults
overwinter, either in galleries at the base of the tree or in hollow twigs, and emerge early in the year, February when
the season is favourable, and begin to excavate brood galleries at the base of the trunk. Development from egg to adult
takes about three months. New generation adults usually begin to emerge in June and move immediately to the crown to
feed on growing shoots through the summer. Overwintered adults also move up to the crown for 'regenerative feeding'
before returning back into the trunks to construct new galleries and lay a second batch of eggs. Adults from this second
brood emerge late in the summer. Hanson states that there is usually only one generation each year although in warmer
countries there may be two. Alexander states two
The ant beetle (Thanassimus formicarius) is a known predator of both T.piniperda and T.minor (Hartig) (the lesser pine shoot beetle), and adults can eat several pine shoot beetles daily. All three species are attracted to monoterpenes produced around damaged areas of various conifers; the ant beetles disperse either before or around the same time as the wood borers and are often present at sites of damage before the wood borers arrive (Byers, 2004).
T.piniperda has a very wide distribution in the northern hemisphere, occuring throughout Europe and east through Russia to Japan, China and Korea; first recorded from the USA in 1992 in Ohio, it is now widespread, and established in Ontario and Quebec around the Great Lakes. The following information is from studies by the Canadian forest services.
There is a single generation each year. Overwintered adults begin flight when the daily maximum temperature reaches 10-12 C and the daily mean is 7-8 C. Adults can fly several kilometres to find a suitable host; they prefer to colonise freshly cut stumps and 'slash' but can attacked stressed living trees. Females excavate galleries 10-25cm long under bark to lay eggs, these galleries are more numerous on the sides of logs warmed by the sun. After laying eggs the adults emerge and die. Larvae feed in separate galleries 2.5-10cm long from April to June. In May or June larvae pupate at the end of their galleries and fresh adults emerge through the bark and attack new shoots on pine of all ages. The beetles damage new growth by burrowing up to 10cm along the pith. During October adults move into the soil or into the base of trees to overwinter. In warmer climates the adults can overwinter in shoots.
The species is included in our Watford list from one specimen attracted to MV at Cassiobridge during July 2006.
3-5mm. Brown to black when mature, elongate cylindrical with pronotum characteristically narrowed anteriorly. Head and pronotum shiny with quite dense and very fine semierect pubescence, puncturations fine and evenly distributed. Head not hidden by pronotum, visible from above. Eyes widely transverse (to longitudinal axis of body), entire or weakly sinuate to front margin. With a short and broad rostrum in front of eyes, mandibles stout and prominent. Antennae inserted on side of head at base of rostrum; scape dilated and curved towards apex, funiculus 6 segmented, club broadly oval and compact, boundaries between segments transverse ie not oblique. Pronotum quadrate to slightly transverse, broadest a little below middle and narrowed anteriorly, without raised borders or sculpture. Elytra parallel and strongly convex, striae consisting of regular rows of punctures, interstices finely and randomly punctured and with rows of upright pale setae; towards the apex these are on small tubercles. Anterior margins weakly raised and separately rounded, witha series of raised tubercles which do not reach the scutellum. Second interstice depressed over elytal declivity, with a few fine punctures but without tubercles or setae. (Anterior coxae contiguous; without a prosternal process between- Duffy, 1954) Legs robust. Tibiae strongly broadened apically, protibiae with small teeth outside before apex, meso and metatibiae with teeth at centre and apex. Third tarsal segment bilobed. Claws well developed, curved and weakly appendiculate.
Description from one Watford specimen at X20
Byers, J. 2004. Thanassimus formicarius. Chemical ecology of insects. www.wcr/.ars.usda.gov/cec/insects/tformi.htm
Hanson, S. 1937 Notes on the ecology and control of pine beetles in Great Britain. Bulletin of Entomological Research. 28:185-236