Agrilus sulcicollis Boisduval & Lacordaire, 1835
European Oak Borer
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POLYPHAGA Emery, 1886
BUPRESTOIDEA Leach, 1815
AGRILINAE Laporte, 1835
AGRILINI Laporte, 1835
Agrilus Curtis, 1825
Locally common though sporadic throughout lowland Europe from Spain to Greece in the south and extending to the UK and southern provinces of Fennoscandia, this species is known throughout the Palaearctic region to Eastern Siberia and has recently become established in North America. The first Nearctic record was from Ontario in 2006, although previous to this specimens had been intercepted at ports, when a single female was found on a sticky trap placed in deciduous woodland, other records soon followed and it is now thought to be widely established in North East Canada and adjacent parts of the United States. The species was first recorded from the UK in 1994 when a single female was found in woodland in South Hertfordshire, more records soon followed and it is now widespread in South Eastern and Central England, records remain widely spaced and in this sense it may be considered local, but it seems to be spreading rapidly at sites where it has been established for some time it is now very abundant. Typical habitats are open deciduous woodland and wooded scrub with plenty of older trees and fallen timber and adults occur during June and July although single specimens sometimes occur earlier or later and have even been recorded in the winter. In the UK the usual hosts are Common Oak (Quercus robur L.) and Sessile Oak (Q. petraea (Matt.) Liebl.) while on the continent it has been recorded from Turkey Oak (Q. cerris L.), Hungarian Oak (Q. frainetto Ten.), Downy Oak (Q. pubescens Willd.), Common Beech (Fagus sylvatica L.), Sweet Chestnut (Castanea sativa Mill.) and Common Hornbeam (Carpinus betulus L.), and in North America it has been sampled in emergence traps on Red Oak (Q. rubra L.) Adults are diurnal and very active during warm periods, they run over fallen branches and logs and fly very readily, alight and run instantly and so can be difficult to spot but they are distinctive in flight and many specimens tend to occur about the same branches or trunks, in cooler weather they remain still low down on trunks or fallen branches but will move rapidly when disturbed. Mating occurs through the season, this occurs on fallen timber and is quick; the beetles taking flight soon after. Females choose damaged or denuded trunks and larger branches to oviposit and usually spend
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some time running about searching for suitable sites, she will eventually insert eggs by probing into cracks and crevices with her long ovipositor and then resume searching for other sites. Larvae develop within bark or between the bark and the xylem, they produce sinuate galleries that are tightly packed with frass and gradually widen as the larva grows, those that become fully-grown by the autumn will produce a pupal gallery in the bark and bore a partial D-shaped emergence hole before they overwinter and pupate in the spring while smaller larvae will overwinter in the wood or bark and complete their development over the following summer and overwinter a second time. Adults emerge from the wood during the first hot spells in June, they generally take flight to nearby trees where they will feed on foliage before dispersing to find mates. Damage due to adult or larval feeding tends to be slight, and larvae frequently develop in fallen branches etc., but very large populations often occur with this species and they may become important vectors of harmful fungal spores. Searching larger pieces of fallen timber on woodland margins or in glades is the best way to find the species, this takes a little patience at first as they are very active but after a while they become very easy to spot and catch with an aerial net as they take flight from the wood.
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6.0-8.5 mm. Elongate and discontinuous in outline, body and appendages bright metallic golden-green, bronze, coppery-red, purple or blue, dorsal surface without patches of pale pubescence. Agrilus species in general tend to be difficult to identify and often need to be dissected, even with the limited UK fauna, but the present species may be distinguished by the following combination of characters. Frons with a shallow longitudinal furrow, keels on the pronotal posterior angles about one quarter of the pronotal length, anterior prosternal emargination narrow and shallow and the process more or less parallel-sided between the coxae, and the apical abdominal sternite distinctly emarginate apically.
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​Head hypognathous and strongly flattened in front, eyes large and transverse, punctation longitudinally confluent above the eyes, transversely seriate in front. Antennae serrate from the fourth segment. Pronotum parallel-sided anteriorly, narrowing and sinuate to perpendicular posterior angles, basal margin strongly bisinuate, following the elytral base. Pronotal surface strongly convex anteriorly becoming flatter towards the base, with strong transverse and sinuate microsculpture. Elytra elongate (about 3.5X longer than the basal width) with well-developed humeral prominence, sinuate lateral margins and rounded apices, surface with dense wide and flat granules and very short, backwardly-recumbent pubescence (X20). Legs long and narrow, femora unarmed and tibiae without spurs. Tarsi–segmented; basal and terminal segments long and narrow, second segment small, third weakly and fourth strongly bilobed. Claws sharply appendiculate.